Both of you are wrong. Not balance at all, in fact it's as realistic as we could get it (except for the overheat thing), I'll have to check with our military advisors on that one. Anyway here's the story...
The actual RoF of the GAU-8 cannon in real life is far higher than the BF2 engine allows. So what we did was give each round an AoE (area of effect) to simulate the higher rate of fire.
In 0.6 the A-10 actually carried 1130 rounds (realistic loadout for them during their early years, nowadays it's 1174 for safety reasons). But then we though about it....why the hell did we give it realistic ammo count on top of the added AoE? That made no sense and essentially gave the A-10 1130 rounds of absolute ownage (coupled with the ineffective AA systems in 0.6 that was a complete distaster, thankfully those days of 24/7 T90 rapage are over).
So, for 0.7 both the A-10 and SU-25 were given AoE on all their rounds to simulate a higher RoF
as well as an ammo count* that reflected it.
* I'm the one that made the ammunition changes relative to the AoE (GASP! I did something other than sounds

). Did a bunch of research on it beforehand as well so don't worry I got it right for both jets.
That clarify things?