[I'm going to play 3.x and 4E]
As a player I'll play either. As a DM I don't want to play 3.x again... eww, eww, eww, keep it off, disgusting! 3.x requires system mastery to play as a player, and a great deal of work to DM. While I have system mastery to make characters and that's all fun and good for me, I greatly await the DM tools and balance 4e to has to offer the games I DM. No longer do I have a party of power houses and others as dead weight.
So if I have no one who wants to run a 3.5 game, then I'll play 4e all the way, but as a player I didn't have a problem playing 3.5 at all.
"Wouldn't it be nice for you to refill the GM's glass right now? GMing is thirsty work."