i fly with small ammo load for fighter sorties and large for attack sorties. if you run out of ammo with small load, usually means time to go home anyways, otherwise your left trying to get kill with those 50 cals. not saying not possible, but...ive had those last 1000 50cal rounds give me 2 kills, or a lot more, but its not worth it. ive stuck around with just 50cals to get my arse handed to me, because a shot that wouldve kilt the nme (if i had 20mm) didnt kill the nme, and they ended up gettting me.
but. like mentioned before, its all in what you like and your preference.