. BnZs is not arguing for a new definition of "unbalancing," rather he is arguing that the best aircraft and vehicles should have an objective definition, namely performance data.
Anax, I am actually more concerned with SpitXVI performance data relative the whole plane set than its performance relative the F4U-1C. Namely, the fact that it is as fast or faster than so much while being much superior in thrust/weight AND turn performance to so much, while simultaneously possessing excellent lethality and roll-rate. Plainly the fact that the F4U-1C has quad cannon alone does not justify its perk status, not in an arena that has free Typhoons, HurriIICs, N1Ks, Fw-190 A-8s, Mossies...eh, I'm not going to list everything that rivals the C-Hog for lethality. You get the idea. The only justification for perking the C-Hog, and one I agree with, is to encourage the use of the more common .50 packing Hogs. I think multiple justifications for perkage ARE acceptable, and are evidently in use.
If we imagine an arena set with three planes in it, say the P-51D, SpitXVI, and a HurriIIC (thought I'd throw in an "irrelevant" EW/MW plane), which one would I consider perk-worthy? Answer: NONE. All of these planes have at least on clear advantage over the others in relative performance. If we were to introduce the La7 to this set, I would say perk it, because at typical MA altitudes it would enjoy almost complete superiority to, and strongly effect the viability of, a very large chunk of this set, namely the 25% of this set that is composed by the P-51D.