I think the controllers are the ones having the toughest time here. It has become obvious to me that Ed Bular's kiss-up to the west pilots was never run past the controllers (the other group that has to live with this fiasco.) The controllers now have to look at the flight tags which have "USAxxxx" and translate that to "CactusXXXX." If you are reading USA, it makes perfect sense to speak "USAir." It makes no sense to say "Cactus."
The controllers should demand that the USAirways designator "USA" be rescinded if the airline insists on using "Cactus" as a call sign. Almost anything else would do. The correct way to pull this off would have been to change the entire airline to AWE designators at the same time as the call sign change. Controllers should have insisted on this, IMHO.