Main reason yes Kev but IMO that is a bad reason to perk a plane in AH as it is quite clear that the vast majority of the fights take place bellow 10k, and when a fight actually starts at 20k+ it usually ends up at the deck for obvious reasons.
Spit 14 has got its best speed at 26k with WEP, 450mph.
Rechecked the G10, best speed at about 22k, 455mph.
Ta152 has got it's best speed (in AH) at about 35k with WEP although the charts we have now no longer show 30k+.
Unperking the Ta152 and you'd see more of them for a short time, few days or a week at the most, not enough people have the skill or patience required for that plane. Same thing goes for the Spit 14 although this is a far superior performer to the Ta152 down low thanks to its turn rate and superior climb rate and I'd say the 14 needs to remain perked, although cheap, 10 maybe?
P47N, we just don't know yet, hopefully it will be unperked in the beginning but I won't get my hopes up. I just don't understand the reason to perk a plane that is fast up high, such a plane will not upset the arena balance.