My idea for Flurry (based off your idea) is for Flurry to gain +10% chance to disorient for each other power from the Speed pool (up to +30% for 3 other powers--increasing the chance to a straight 50%). Each other power would add the following to Flurry:
Hasten - reduced animation time (while keeping the same damage throughput)
Super Speed - adds mag 1 stackable stun
Whirlwind - adds a cone
Burnout - adds a non-enhanceable fire DoT
The exact numbers for these would be tweaked for fairness, of course.
Many heroes end up taking Hasten (because it's so good), and Super Speed as a result. So many applications of Flurry in this situation would be a 40% chance to apply a mag 3 stun, while keeping the same dpa, but having an increased dps, which I feel is a pretty fair in most situations.
What I would like is a customizable animation for Whirlwind, where I can turn off the spinning animation (keep the character in a normal stance while keeping the whirlwind effect) or maybe changing it to a vibrating animation.