I agree with Hazed. Don't let this perk thing get out of hand.
The problem with the perk system is that it assumes that good pilots will earn perk points to spend on these planes. Actually, that may not be the case.
Remember that most pilots that like the perk system do so, because they spend a reasonable amount of time flying to enable them to accumulate enough perk points. Remember also that there are quite a number of pilots, paying the same price, that don't have a lot of time to spend flying to allow them to accumulate a lot of perk points. Now both of these pilots could have the same relative skill level, but the pilot with more time available can accumulate more points. As a result the perk system does not really reward only the skilled pilots.
The more planes that are reserved for perks means less planes available to those pilots, paying the same price, that just don't have a lot of time to accumulate perk points.
Eventually this would lead to defections by pilots, paying the same price, that don't always have the same opportunity to fly those perk planes that other pilots are enjoying. Now this type of system might have worked in the old pay by the hour sim, but in a flat rate priced sim it could bring problems.
A better system is really needed. Something like enabling a certain number of perk planes for a country as it starts to loose bases might be an option. I really don't have any good suggestions, but then again I don't really think the perk system is a good idea.
Be carefull what you wish for, because you just might get it.
Ranger Bob