I took Kaleidoscope for a spin when I was trying to find a way to diff two PDFs.
As I understand, Kaleidoscope extracts the text from Word files and compares only the text. That’s good, but not quite as good as actually comparing two Word files with all their formatting intact.
But, the insurmountable problem with Kaleidoscope is that there is no way to print/save/output the comparison pane that it creates. In other words, there is no way to redline a Word document in a way that can be shared with someone else.