If I remember correctly the Spit 9 usage has dropped considerably since AH2, must be a reason?
I know Im going to get ripped apart for saying this but that never stopped me in the past... So.
I would say... The reasons we see the SpitV being used so much more than the Spit9 and probably many of the other planes is because it is such a simple and forgiving plane to fly. With a little alt, and a little bit of speed and know how you can basicly live fairly well in a SpitV. If you get caught up low, on the deck, with multiple cons, thats a different story. But if you have alt, say 10k... And mantain your speed you can live a very long time within this plane.
I personaly find the 9 a far superior plane to the 5. When its low on gas, around 50% say, you can turn that thing VERY well. When you keep it slow by chopping throtle and getting it into flaps the spit9 can hang in a turn fight with a spit5 for quite a while. And if it gets into any trouble, it has a chance to accelerate away from the Spit5 or out climb it with its better climb. The 9 CAN turn like a monster if you know how to keep it in its sweet spots. Its not a better turn fighter, but it is a great one. And it has the speed and climb to hang with alot of the better accelerating planes out there.
To be totally honest Morph fed up of the endless LA7, D9, Ponys. People are asking for MORE planes, we use what maybe 50% , prob less of whats available now.
I can understand that. But... Do you honestly want to be chasing another plane down? I think not.
Because that's what will happen. You'll see everyone who used to fly La7s for the reasons you've already listed, jump into spit14s.
We dont need another unperked runner.
P51's
P38's
190 D's
109G's
Tiffy's
La7s
So you learn techniques/use techniques you already have to sucker them into a fight. One they cant get out of until one of you is dead.