i agree infantry should defened at two,
however airborne is different from infantry.
infantry have trucks, anti-tanks guns, anti-tank rockets, feild artillery, mortars, heavy machine guns, armored vehicles, entrenching equipment and the supplies for it.
airbourne, have recoiless rifles and maybe mountain guns
naturally infantry are going to be much stronger on the defence
in fact airborne probalby should have no attack value at all. This is due to the fact that i have no knowledge of airborne units being effective at any conventional attack.
the only attack airborne should have is a 3 or less attack at the begining of a combat where they are deployed by air and of course they get to choose the causaulty, i do not understand why no one else agrees that having airborne units choose their target is extremly realistic.
of course they should still defend at one, cost 3 to build and 3 to do an airborne attack. also they should have range of two since no airborne attack was done at a range longer than that.