Since we're talking about a game that puts different planes form different eras side by side remember that the real issue is gameplay balance -- not realism or potential killing power.
So in the MA, are things unbalanced? I'd have to say no. There is no superplane that can't be killed; even the low perk uberplanes many complain about are shot down very frequently -- slice by death total, kills per death, whatever. Yes, you see a lot of pony and La action -- but they die lots too, out of proportion to their theoretic quality BECAUSE they're flown by less skilled pilots on average. Some ACM people seem to wish that everyone flew a spitV, so the stars can show how much better they are -- btu that's not gonna be fun for the rest of us.
Don't fix what isnt broken. AH's planes are balanced byt he current perk system, and while that's not set in stone changes should be based on imbalance provable by the MA numbers.