The R7, R8, and R9 all have the same neck shape, except they get slightly smaller (and more desirable) as the years progress. The differences are small but definitely noticeable. That said, I find them all to be pretty comfy. The R7 is the Gold Top, the R8 is the Plain Top, and the R9 is the Flame Top. The best buy, in my opinion, is the R7 because it is the EXACT same guitar as the R8s and R9s, except they're typically on the heavier side, have the already mentioned fatter neck and are usually cheaper. I think all of the newer ones have Burstbucker 1s & 2s which aren't as hot as the 2 & 3 combo. The R9 is GROSSLY overpriced. I certainly wouldn't mind owning one, but I'd rather get good deals on an R7 and an R8 and have two of those for the price of one R9.
Edit: Also keep in mind that the 2012s have the 2-ply laminated fretboard. Dunno if that matters to anybody, but I wouldn't want one.