I have used paratroopers with great and perceived balance with these stats:
Air transports may transport one infantry (or elite infantry) aboard either for combat or noncombat purposes. This infantry (a.k.a. paratrooper) may be picked up or dropped off anywhere along the air transport’s flight path. Paratroopers attack and defend in exactly the same manner and at the same values as standard units. When attacking with paratroopers, any AA gun hit on an air transport also destroy the paratrooper unit aboard.
Return Home After Dropping off Paratroopers
Air transports do not have an attack value because their role is to deliver troops to the battlefield. Therefore they do not participate in attacking land (or sea) battles after defending AA guns fire. After dropping paratroopers into the battlefield it is understood that they have disengaged from the battle and are returning home. As a result, they can never be chosen as causalities in battle, although the infantry they carried into battle could.
Chosen Last as Causalities.
Like transports in a defending land battle air transports are chosen last as causalities. Meaning if a territory with air transports are captured by an enemy all air transports in that territory are immediately destroyed.
A Note on Technology:
the current AAG40 tech chart will need to be changed. Paratroopers may be replaced with giving air transports the ability to carry two infantry (or elite infantry). Just a thought.
A note to those advocating 2 infantry per air transport:
I have found this to be a bad idea since it encouraged players to fight battles with a few paratroopers some fighters and no supporting land units. Limiting to one infantry means that players will usually bring in additional supporting land units giving the unit a more historical feel.
Once again Thank you FMGs.