One follow-up – it looks like Apple’s got an adapter that will let me connect my current Time Machine backup drive (FireWire 800) to a new machine’s Thunderbolt port. So instead of making a backup from the old machine to a new external drive, I’ll just point Migration Assistant to the Time Machine backup and hope that will do the transfer. I’ll probably plan to migrate on a weekend so even a slow migration won’t disrupt work.
Dave