A Sabin-like class would be cool too. Yes, I know it's based off of a monk, but if you were able to do a few DDR-like button combos for a big TP move I think that might be interesting.
I agree and disagree. A problem would arise dealing with lag and server load and such where fighting game inputs could get lost and cause heavy problems for people playing the class, and there's also people that might simply not be dexterous enough to pull off the moves themselves in in optimum settings. But, like Kanon, you could just set it as a combo. You start inputting a simple first level move, that branches off in two directions for a medium move, and each of those two moves branches to two more moves to build up combo points, and you build enough then you can instantly pull a full combo in a single combat round using 1+2+3 in rapid succession.
It gets the basic idea out without punishing lesser machines, connections, and players.