I talked in the post about what I had first hand knowledge. And since I have not (yet ?) come across too many bugs on the PRS-T1, I haven't tried to contact the support service.
On the other hand, I've established a
list of bugs for the Odyssey, sent it to Bookeen, and have received almost no acknowledgement of them, and found them lacking in communication too. (additionally, they don't have any real forum to discuss about the bugs so ...)
As for the Nook, I know when I imported it in France that I would have no support, so didn't even try.