I switched to Dancer a few weeks ago, and from my own playtesting, I'd mainly like to see four things.
1. Removing cooldowns from Fan Dance abilities if possible. Having to deal with that cooldown while trying to manage my GCD at the same time is kinda clunky.
2. Having Standard and Technical Step replace the AoE combo on usage. Just a QoL change that'd make AoE'ing a lot more convenient for controller players.
3. Having Saber Dance be oGCD, or remain on GCD, but carry a DoT effect for a touch of added complexity.
4. Improvisation actually made usable outside of fringe cases. Maybe a per player chance of a feather proc every tick?