[Snake]

Bard
Bard's Dance skills could use dealing Physical Damage instead of Magic Damage. You would see more creative combos being made with things like Kensei's Absolute Death, or more obvious counters like Black Knight with this change made.

Dancer
Rest Beat as is seems to be a little too 'free battle redo' button, especially when Spirited. It can even be further paired with Cantus of Consideration for even more debuff removals, making it so they're completely clean in a single round with two buttons pressed. The only solution to this in my honest opinion is making Rest Beat cost 6M+, and have a minimal requirement of 4+ Tempo to be used.

Idol Step, aside its bugs, should NOT heal the user at all through its ticks. I don't think many people will disagree that this should be more a team fight technique rather than a decisive factor in 1v1 combat. It gives this class way too much unnecessary sustain, and promotes them to be unkillable tanks, since Interference doesn't do much to stop them due to Consideration and/or Rest Beat.

Tempo alone could use another counter to make it less easy to be built up since it passively goes up as the Dancer does their deed. Perhaps being inflicted with Clumsy, Immobilize, Frozen and Knockdown could also reset it to 0? It's not like inflicting a Dancer with any of those things is easy anyway, when they are a dodge-user.

Performer
Slydria has already made a thread on this, but I'll have to chime and say that this is by far the least fun of the trio. There was put too much glorification on Dancer to the point it's now the most used class not only out of Bard's promotions, but probably the entire game now. While this was left sucking its thumb.

The problem with Performer? It's way too "balanced". Where is its damage? Its autohits since how the hell does an enemy dodge music? Its techniques to grant allies momentum or even an incentive to make them stay in the Singing state that is not "ok you dont need to buff them this turn anymore, also have this +5 HP/FP and some Evade".

This class has so much potential still yet to be tapped, but I feel like Dancer outshined it by a long shot. It's just sad, but that's all I can say. If a proper buff is to be given, at least grant them one more 'song' that is more generalized around dealing damage and Sound damage, which is also an auto-hit or whatever.