HT.. I'll admit that the only reason I care about your new side balancing idea is because I fly the P-51D all the time. If it is disabled, then I have to start jumping countries to fly it.
May I suggest, that rather than disabling said aircraft, how about turn them into perk planes?
Using the same code that would trigger the planes to be disabled, just turn on perk values for them at a reasonable starting price - in the range of the F4U-C.
Of course then, if the number disparity becomes greater, the price for the perks goes higher, as it does with all other perk planes currently.
I think by this means, you will effectively accomplish the same thing because people can switch sides to fly them for free, but dedicated squads or players that only fly a certain aircraft won't have to switch countries if they are willing to pay the perk price.
How about it?