Oh, I don't know, I think an "X-Planes" arena COULD be cool. But again, make it a SEPERATE arena, or put a HUGE perk on the X-Planes.
Besides, WWII: 1946 was about the coolest part of Aces of the Pacific (as if that sim even NEEDED more coolness than it already had. Best...WWII ims...EVAR).