"Who does that? Not many. It is stupid in any case. "
Stupid huh? No stupider than, say, someone who picks an F6F when there's the N1K2 that out-everythings it available

"So what I get is that you are basicly complaining that you are invulnerable to the slow planes but it all evens out because even tho you can kill them with impunity you can't do it very fast without taking risks? "
Invulnerable? LOL! Why? Because it can run?
By your same flawed logic a Spit 5 is invulnerable to a P-51 because it can dodge the P-51's attacks indefinately with maneuvers that the Mustang can't hope to follow. And that is how it frequently plays out in the arena--alone, a Spit 5 against P-51 will commonly result in a draw with neither plane able to kill the other.
The difference is that the guy in the nimble plane will be making a jerk out of himself on channel 200 yelling "come back here you wussy runner"......while I can't remember ever seeing somebody telling the Spit guy to quit maneuvering.
I see it as balanced, at least in the case of the P-51. I am NOT talking about things like the 190D-9 or LA7--both of which are generally superior to the Mustang IMO. I don't fly either enough to really comment on how balanced they are for the MA ( heck I don't think I've EVER flown an LA7 online).
Take the snide undertones out of your post and I can see that even you know the balance inherent in the situation, although both of us know that there'd be no harm in having an area designated specifically for extremely early models which have no chance in the MA. Being slow by itself isn't the problem that people seem to protray it as. Nobody calls the N1K2 "underpowered". Being slow with no firepower and bad E-bleed....now there's a problem.
On and tell me why you seem to think that Spits and N1k's and such never BnZ slower planes in furballs either. Heck a BnZing Spit might be the most deadly plane in the game.
J_A_B