Still content on RB is way beyond GH3 currently.
My biggest gripe with RB (One reason I rarely throw it in the 360) is the actual control of the game in general. Being a guitar hero freak, (Over 2700 wins now) ...RB is lightyears behind GH3 in terms of simple things like hammer on's & pull off's (Miss every one btw) & basically the layout of them horizontal notes is um..

So, yeah, kinda takes the fun right out of the game for me. So what if they have all the best artists songs if ya can't get 100% notes hit on any of them!
If the gameplay was identical to GH2 or GH3, I bet I'd never leave RB.
Sorry, I'm a perfectionist on guitar & when I miss a note I know I hit, it just ain't fun.