@Blade: Not really. Ideally, a balanced party doesn't want a bunch of performers anyway. If you have seven performers, one healer, and one knight, then that's six performers who are nothing more than sacks of meat for enemies to hit. The performer already balances itself by making having performers redundant beyond two (they already can't perform each other, and no unit can take more than two turns a phase regardless), and if you have a house rule of just one then it's perfectly fine. Especially since, again, this is a class that you're not going to see a whole bunch of every FEF anyway. There's only been one game with two in it, and most people want to be on the front lines getting into the action. For the majority of players, it's much more satisfying to be the guy who went out there and critted someone with an arrow so hard his head is pinned to the column seven tiles away than it is to be the guy who sat back and played a song for the sniper. It's like, say, basketball. People only care about who got that sweet dunk; rarely do they notice the player who passed the ball to the scorer. Only people who have a particular idea they want to play (like FFS with Candy) or who like playing support classes (me) are going to pick it.
@Birdy: That's also partially the GMs fault. The only performance item I can recall getting is a Hermes Whistle for Powder's character in Gates of Rundum. There will quite likely be situations where +5 RES is more desirable than another turn, but if the party tends to prioritize buying damage-dealers and the GM figures double-turning is good enough that no performance-related loot is required, then you have a situation where yeah... that's all performers can do.