Yes. I don't think it's the ammo, though. I think that might be in the gunpod itself. Not totally sure. The gunpods occupied some of the space, though, as well as blocked the bulges for the ammo canisters for the MG/FF. You could not have kept functional MG/FF with the gunpod.
Also, the MG/FF aren't nearly so bad as suggested in here. They're not AS good as MG151/20s, but they are still good. When you set the convergence the same, they will hit at the same point (with variation for recoil of individual guns). They "lob" a bit more, so if you're trying to get max-deflection shots and nothing else, some of them will miss.
I fly both with and without the outboard guns. When you want a bit of a boost, go without. When you want the extra firepower, take it. The A-8 is worse with outboard guns installed than the A-5, but still it makes a difference.
I've done the "light" thing with A8s and I've done the "take 30mm into furballs" with it. Either way you're fighting against the odds, but it just depends on what you want to do at any given time. It may get you killed more, but it sure is hilarious to pop 2 targets in a row nearly instantly with those 30mm fireballs. After that, you may be SOL, but until then you'll have some laughs.