Sorry, I have to disagree. I think it would have an excessively negative impact on new player retention as they were blocked from the three most potent Spitfires and the P-51D, as well as less well known fighters such as the La-7 and N1K2-J that also make it a bit easier for new players to get into the game.
It would also have the negative effect of making anybody in a P-51D, La-7 or Typhoon even more timid while Spitfire and N1K2-J populations would plummet (some people would think this a good thing) due to their inability to run and protect their perks. Bf109K-4, F4U-1a, F4U-1d, Fw190D-9, Ki-84, P-47M, P-47N, P-51B and Spitfire Mk IX populations would likely increase in percentage. The MA population loss due to the P-51D being perked might be significantly large.
I do not think this would be good for the game.