Hi,
I am in a hurry, but will try to reply now, before going to work:

1- Bass: depends on your taste; if you play a lot of bossa nova or acoustic bass, I find that the T2 acoustic bass is too heavy and invasive. Anyway, there is a lot of choice, and tweaking here and there you can come up with something interesting.
2- Piano: yes, I think it's different and with a warmer sound; much better than the PSR. Of course, the biggest drawback is that it's very difficult to play a piano sound from a non weighed keyboard.
3- Percussion: you won't be disappointed with the T2 percussions; what I find lacking are drumsets for dance, hip hop or techno, but I don't play much of that stuff so...
All in all, if your are after emulations of acoustic sounds (including percussions), go for the Tyros 2 and you won't be disappointed: promise!

[This message has been edited by Dreamer (edited 05-09-2006).]