Assuming you don't care for looks, and assuming GH4 supports GH2/3 guitars; GH2 game + controller GH3 game + controller Rock Band game + drum Headset GH4 game + drum So you'll end up with 1 Xplorer, 1 Les Paul, 1 RB drum and 1 GH4 drum and 4 games. This way you can save your money on: RB mic and GH4 mic - headset works just fine except it's hard to tap when you're playing another instrument at the same time RB guitar - not compatible with current GH games and presumably future GH games as well GH4 guitar - if you already have two, then... RB drum and GH4 drum do not seem to be compatible because of different number of drumheads (and cymbals =P). While I do love rhythm games, I don't like the flood of peripherials. I mean 2 beatmania controllers, 2 taiko drums, 4 guitars, 2 drums, 4 mics.... Come on.. Don't force people to buy bigger homes so that they can store all their rhythm game controllers.. What's the worst thing that can happen? Harmonix announcing Rock Band 2 with a new drum controller with 4 drumheads and 2 cymbals.