The big problem with the f4u4, and spit14 is thier tags. The cost isn't the problem. These planes are not much fun to fly in BnZ type attack, and free planes will all do it just as well. When you have gangbang tags, that is the only type of fight any plane can survive.
A spit14 or f4u4 will outperform another plane dramaticly. However, against five, the performance difference isn't going to help you.
The bottom line is that, the gangbang tags require the planes to be flown too conservatively. If you get into a position where more than one plane can target you, you're going to be forced to run, or possibly killed. Flying like this requires spending too much time getting altitude, too little time fighting, and as the usage stats show, obviously isn't fun.
Me262: 1158 kills
Tempest: 724 kills
Spit14: 376 kills
F4U-4: 297 kills
C-47: 365 kills