I want in on the fun. So make your requests and I'll write up tiers for 'em.
Length-wise, I'm gonna go with the RBN limit of 10 minutes. Sorry, but if your garage band has this transcendentally perfect 45-minute opus that you trying to spread around, I'm gonna have to pass. You're welcome to still list it, and I'll probably give it a shot, but I couldn't possibly listen to something that long and have something constructive to say about it. I'm a child of the 90's - blame MTV and Ritalin.
Please don't submit anything like that SNMT garbage that's on RBN. If its creators actively mean to cause people physical pain by listening to it, then I'm not gonna bother with it. Short of that, though, I would have no style restrictions. Try to keep it as stuff that would make sense in the game (i.e. not stuff that would only be 1 or 2 instruments), but even in that case I'd still listen to it.
I think this could be a lot of fun, but it's not something I've tried to do a great deal before, so bear with me if I make what you view as obvious mistakes. I have very little experience drumming, so that's probably the biggest potential for discrepancies.
With all that said, request away!