It has nothing to do with screwing up your fighter standings.
See, living is meaningless. In fact, if you spend the time flying back to base your wasting time you could be spending killing people. Kills per time is a very important category for fighter, attack, and vehicle ranks. Your gunnery can be higher, but if somone kills more frequently then you, they will have a better rank.
In attack, your bullets count when you hit any kind of target. They count towards gunnery that is. Bombs, in attack mode, are counted for accuracy. Dumping your eggs before you get to target, will degrade your accuracy.
In fighter mode the only thing ammo is counted for is hitting enemy aircraft. I think it may count on enemy vehicles, but I'm not really sure there. I don't shoot at GV's in fighter mode, unless it's mandatory. Bombs in fighter mode are meaningless, and ground kills are not counted as fighter kills.
Now, if you don't care about rank, just kill stuff. However, it's not too hard to just press the right slot button (Fighter/Attack) before you launch. You know if you are carrying eggs, or rockets, that it will probably be an attack sortie.
The perks you earn in attack mode are counted as fighter perks.
BTW, that 28 kill anti-GV attack sortie I had the other night earned me 76 perks, and took only 30 minutes (probably less). Only six of them were kills earned with eggs.
By definition any anti-GV Attack sortie could be considered a vultch, but you have to remember those Ostwind's can shoot back, and so can the M-16's. Even the lowly M-8 and M-3's can kill your radiator, or knock a wing off if you give them half the chance.
Do you think a pilot that's out to survive would even think about trying this? Ergo: Attack. My favorite category.