Also, I don't know how it works in Guitar Hero, but what should happen when you send a "Difficulty up" to someone already on Expert (or the highest avail. diff for that song)? My suggestion would be that if the difficulty doesn't go higher, then treat the attack the same as double notes.
Other than that, battle mode is actually a lot more fun than I thought it would be. Especially since on my key configuration I had jurgen's star power key mapped right next to my own, and I kept accidentally hitting it and attacking myself
