No, the sides don't have to be equal. I'm in agreement with you on that. However you do have to provide at least a minimal amount of options to the allied planes. Hurr2C has guns but it's too slow to be a contender with almost every one of the axis planes. Moss is fast but can't turn worth crap, so basically it's a frustration machine (line up a BNZ, enemy turns, extend, repeat, never get a kill, rtb no gas, get vulched landing).
So basically the only competitive allied fighter is the spit9. And spit9 is good, but vs half a dozen various enemy fighters? Gets a bit old, I'd imagine.
Just an opinion