I used this with a winged PC I once.
Manouverability becomes a DC range eg Poor Manouverability = DC 0 - DC 15 whereas doing something like flying backwards at full speed would require Perfect manouverability DC 40 - 50
Personally I beleive that all movement should be combined into a single dex-based Manouvere skill which applies to the characters main move type (run, swim, fly, climb whatever and also cover things like balance)
DC 0 Walk, Glide etc normal movement with no effort required
DC 20 Run across uneven ground, fly in built up area (eg amongst trees, between houses), swim in rough water
Wingover DC 20? Hover DC 30?
needs work