Never tried; but a 1 asf / 4 sf or 1 asf / 4 eaa the asf absorbs most of damage.

It all depends on mix. Damage is split between types in a stack; so if 1 ASF (will receive 50 pct of overall damage) the other for will split the remaining 50 pct. Wouldnt do this with choppers and better to keep ASF separate and patrol ahead of the choppers (if isnsist on using choppers as 1 EAA is wat better than 2 Choppers)

If you stack choppers or EAA with strike fighters or asf their speed and radius is reduced to the lowest in the stack. Means more hits from AA. Personally I would not combine them because I find choppers are more useful than ASF. Not too sure about how damage is split but just the reduced speed is enough to deter me from this.

If you stack asf with choppers, they can also be chased more easily on the way back to refueling since range is shorter and speed is slower. Missiles, SF or gunships can come and ground you

.

Its free dmg reduction early on, which is pretty useful because you dont have a high level hospital at that point yet. But this is only if you stack the asf to absorb dmg for the helis; asf in general have a pretty high weight in terms of dmg distribution

Tho I think that since dmg gets split in stacks, helis might absorb some of the dmg SAMs would to the fixed wing aircraft in a stack.

But yeah, def wouldnt stack shit with asf if i plan to hit other aircraft with it.
Especially would not use a stack with such a bad synergy for longer than absolutely needed; so def not beyond maybe day 10