The only way I applied the QuBon to Flying is to combine it with the AgBon on maneuvers while flying. I NEVER applied to add to the flying speed. However, arguments could be made that it should.
My Logic: Quickness only tells you how quickly you can react and maneuver while flying. Agility tells you how gracefully you make those maneuvers.
To increase flying speed, I would require the character to make a MM roll using Self Discipline and Presence as the stats, then roll on the Very Hard column at least, perhaps higher.
I feel it is the character's strength of will that would be used to increase speed, agility/quickness on maneuvering.
Just my thoughts.
rmfr