I'm not sure I understand the mechanism which causes players to change sides in significant numbers.
I think most of the squads are fairly stable -- they stay with one country or perhaps rotate on a monthly basis.
So Hitech/Pyro, how about drastically altering the perk equation? Tonight at one time, there were approximately 260 rooks, 150 bishops and 110 knights.
Under extreme circumstances such as those, the knights should have been flying 262/F4U4s/Tempests for free!
An similar modification should be made for perk points earned.
If you switched sides simply to create an imbalance and you're seeing nothing but enemy 262s and Tempests, maybe they'll switch back when possible, or even better, think twice before they create an imbalance.
curly