TB3 vs 4 is a different story. Both have the same top speed (40 Gbps), but TB4 makes mandatory a few features that were optional in TB3.
TB5, on the other hand, increases the bandwidth - up to 80 Gbps and potentially up to 120 Gbps under certain circumstances (when data and video are used together on one cable).
Whether or not you need the extra bandwidth depends on what you’re doing, of course.
True…TB5 is faster by spec but it’s more expensive, requires a Mac with TB5 ports…and for the vast majority of users the speed increase is pretty negligible from a time saved point of view as the time for things to happen with TB4 is generally slow enough that even cutting it in half which is optimistic probably doesn’t really save significant time anyway. A year from now ow TB5 devices will be more common and cheaper though. Remember…better is the enemy of good enough and one should compare the cost vs gains before splurging for TB5 devices…I’m not denying the theoretical faster performance, just recommending balancing cost vs utility.
No doubt about that. Whether you need the higher speed depends entirely on your use-case.
If you want/need to run video over the port, then TB5 (assuming your Mac has the support) is a big deal, since the bonus 40 Gbps for the video stream will free up a lot of bandwidth for other devices sharing the port.
For a storage device, if you’re using it for a relatively low-bandwidth application like Time Machine or a media server or archival backups, it’s a waste of money.
If you’re using it for high-bandwidth active work (e.g. editing 4K video), then you will probably benefit from the extra bandwidth. Assuming the underlying SSD(s) are fast enough to benefit.
And, of course, since Thunderbolt is, at its core, PCIe, other PCIe devices may also benefit, depending on how much bandwidth they require. Back when external GPUs were a thing in the Mac world, that would see massive performance gains (and they probably will in the PC world, where it is still a thing).
If you do a lot of networking (server work?) then it would let you connect very fast Ethernet ports (e.g. 40G or several 10G interfaces) without consuming all of the port’s bandwidth.
But in general, I would agree with you. If you don’t have a specific requirement, then you probably won’t see much benefit.
This is also why I’ve been using 10Gbps USB enclosures for my external SSDs instead of TB enclosures. For what I’m doing, I don’t think the extra expense is worth it.
These are good points about TB5. For me, the sweet spot is connecting a TB5 hub to a TB5 port on my MBP with one TB5 cable, and knowing that the hub will handle image serving off one drive, a CCC backup to another drive, keyboard and trackpad input, and video out to two external displays with no hiccoughs or glitches (thanks to the mega-bandwidth) — and power my Mac and displays at the same time.
Dismount the drives, unplug one plug, snap the lid shut, and my workstation is magically a laptop again.
@Simon, I think I’m pulling back on the idea of Thunderbolt 5 and the highest performance. What do you think about the combination of
and
I looked at other cases, but a lot of the no-name brands recommended in the past are “currently unavailable” on Amazon, which doesn’t give one the warm fuzzies. Although the OWC Express 1M2 is a bit big (I do like the form factor of the little Samsung T5 that I use for Time Machine), I figure the heat sink design might be best for longevity.
The Samsung 990 EVO Plus is a bit cheaper than the 990 PRO, but it doesn’t sound like I’d hit the ways in which it’s slower.
I’ve actually never bought an EVO Plus, it’s been only PRO for me. But at 4TB the PRO is indeed pricey (unlike at 2TB). I think $240 for a 4TB stick is a pretty good deal — I doubt the Crucial P310 or this 990 EVO Plus will in real-world applications show a clear advantage one way or another. If the WD Black SN850X were cheaper than the Samsung, I’d go with that. But as it is, it’s more expensive so the 990 EVO Plus would be my pick too. And the case is IMHO a complete no-brainer, as in my initial recommendation. Have fun! 
This combo looks like a good deal. For years, I have been using a TB-3 Envoy Express enclosing a 4TB Western Digital NVMe with no problems of reliability or speed.
I’ve ordered the combination of the OWC Express 1M2 case and the Samsung EVO Plus SSD. We’ll see how it works in a few days! Thanks, all!
Acasis has a Thunderbolt 4 case (of which I own two, and they are wicked fast) and they just put it on sale for $60…
That’s a Thunderbolt 3 device (uses a Intel JHL7440 Thunderbolt 3 interface chip - the chip is 7 years old). Yes, it supports 40 Gbps TB, but because it’s a Thunderbolt device it’s speed taps out at 2700 MB/sec and can only be used on devices that have TB 3 or 4 ports.
The OWC Express 1M2 is built on a newer USB-4 interface chip ( ASM2464PD) that has been discussed may be more expensive, but has higher performance (up to 3800 mb/s)as well as wider system compatibility since it supports USB.
My guess is that the Acsis device is a close out item.
My big problem with this enclosure is that, like many others, it doesn’t have a cooling fan. SSDs tend to run hot, especially when accessed at high speeds. The passive cooling solution (aluminum fins and thermal pad) may be enough to keep the SSD from overheating, but it is going to get hot, which makes me uncomfortable.
How is this a problem? For a peripheral that doesn’t have any pass-through ports, TB3 and 4 are effectively identical.
And it will be compatible with USB4. USB4’s spec requires compatibility with TB3 devices.
Nah, @Technogeezer is 100% right. There is no reason these days to recommend a JHL440-based enclosure when AMS2464PD can offer ~40% more throughput in real-world use thanks to move available PCIe b/w. I went through all the relevant details a while back, mostly still valid.
Also, the fan suggestion is IMHO ill advised. USB/TB4 and even 5 limit these NVMe SSDs to moderate throughputs meaning that any decent modern NVMe flash will not throttle at typical throughputs they see — very much unlike what on-board flash on Apple silicon Macs or socketed flash on PCs could see where they are not bottlenecked by a narrow TB bus (max 4x4 lanes). This has been tested real world by many, including Howard Oakley and there is no evidence that fans help with performance or longevity if you use an otherwise well constructed passive enclosure. One of the great benefits of going SSD over HDD is silence. No need to make a SSD noisy by adding a small and obnoxious noisy fan to what otherwise could be a whisper quiet setup. Obviously, if your desk is in a noisy environment that’s not an issue, but it remains true that there is no evidence these cheap little fans accomplish anything other than make some people feel better about their purchase. That’s OK too, but it’s important to be clear about real and actual benefit.
Well, a comment in a discussion thread associated with an article that doesn’t talk about fans isn’t exactly a scientific study.
But when he says that passive-cooling devices don’t get hot, I wonder what he’s using. Mine get quite hot to the touch. Hot enough under stress (like when compiling a Linux distribution) that I’d be afraid of getting a minor burn from touching the fins.
Whether or not the device throttles, that’s too hot for anything that sits on my desk.
I got the OWC 1M2 case and the Samsung EVO Plus 4 TB SSD yesterday, put them together in 2 minutes, and have been happily dumping data to the drive ever since. One of the source drives was very slow, so it took about 15 hours, but getting data off the iMac’s internal SSD was fast. And the SuperDuper backup I ran to another APFS volume on the drive was super quick.
All in all, a highly positive experience so far. I have less than 2 TB of archival data, so I can continue to use a 2 TB hard drive as a local backup for that stuff, and the next step is to set up Backblaze.
It uses the aluminum fins approach for passive cooling, and although it is warm to the touch, I don’t worry at all about burns. It might even be welcome in the winter when my hands get cold. 
Today’s AppleInsider has several enclosure and storage recommendations for build-it-yourself SSDs:
While doing some searching, I ran across this product, for which I can only say “WTF”? Amazon: ORICO Dual M.2 NVMe SSD Enclosure.
This is a “dual drive” enclosure that accepts two NVMe SSDs. But it is literally two single-drive devices that share a common aluminum shell. You even need to use two cables if you want to access both drives at once. I completely fail to see why this is anything other than brain-dead nonsense.
Any dual-drive enclosure needs to have a single interface, whether the drives are configured as mirroring, striping or JBOD.
much appreciated! I love this website. Great articles, great forum. I’ll be looking out for them on Black Friday. I just bought a Lexar 1TB drive, I was amazed at how fast my new 14" MacBook Pro with M4 Pro , via Carbon Copy Cloner, wrote to it. crazy!
I bought a Samsung PRO 8TB NVME M.2 and put it in an Acasis enclosure. Would not mount on Mac. I found plenty to document this and was very frustrated so sent back to Amazon. Patrick
As @Simon mentioned, I tend to buy drives and enclosures that can be upgraded separately as tech/prices change. I’ve been using an external TB4 NVMe enclosure from Acsis for 2 years with my MBPro and very happy with it. Also been using a Tekq TB3? enclosure to boot an intel iMac with a Fusion Drive, so so much faster.
The TB4 enclosures are inexpensive these days, and you can choose your M.2 drive based on speed/price that matches what you need.
I have the Acsis TBU405 (no fan) with a WD Black SN850 2TB drive inside. Believe I speed tested it and might have even posted the results in another thread where we were talking about TB controllers, can’t remember if the drive or TB is the limit, but it’s more than fast enough for anything I need.
Or if you want to future proof with TB5 there is the TB501/TB501Pro. Even with higher price and cost of good 4TB drive (see below), still no more expensive than Envoy Ultra (currently $599). The Envoy Ultra has the same chipset as the Acsis, but you can upgrade the drive in the future if desired.
Tom’s hardware comparison of SSDs
Make sure you’re not overbuying on the NVMe, for what the chipset, PCI version and lanes in the enclosure can handle. For example, the Intel JHL9480 (used in Envoy Ultra and Acsis) supports PCIe 5, but you’re unlikely to see any gains from a PCI5 NVMe and you’ll pay a lot more for one right now.
EDIT: Just noticed the Envoy Ultra 4TB is $499 on Amazon, $599 on OWC’s website! (where I had looked for the tech specs)
Acasis has just introduced a new 2-bay RAID SSD enclosure for Thunderbolt 4 that offers almost 2x the speed of a single SSD enclosure when configured for RAID 0. You can also daisy-chain them in LARGE mode that creates one large disk of all the capacities combined.