There are guitar issues too i guess, with the strum bar. Some drum sets either not working right (hitting red also triggers green or blue) or not working at all (game sees drums as a controller, so defaults to voice)
Hope they get it all fixed up, and not just via 'send us your jank hardware'... hope some of it can just be patched
Let's not forget that a number of people had issues with the RB instruments as well. Some would argue that the RB drums were never "correctly" made and not fully responsive (go to Scorehero to see some stories of that.)
Looks like there's already an issue with WT:RB instrument compatibility:
i have both rock band 2, and GHWT. The rock band 1 instruments do work with GHWT, as does both for rock band 2. I also had the PS2 release of rock band, and the PS3 versions of rock band 2 and GHWT. Hope that helps.