Merkinball
Deity
Actually, at first, it made it a LOT harder! I sat down all super-confident, but all the "drums" are in the wrong place, and I found myself reverting to instinct (I knew how to play most of the songs on the real drum set), instead of what was on the screen. I failed the first few times I played on Hard/Expert.
I do think if one is able to score highly on expert, they could play the real drumset and not embarrass themselves. You won't be good enough to go on tour, but you could do it.
This is how I am with guitar hero. I constantly end up screaming "IT DOESN'T WORK LIKE THAT!"