If you have never been shot down by a spinning buff or fighter, then why are you asking for this change ?
Also, why would the degree of turn or G forces limit a gunner's ability to hold down the trigger ?
Currently, if a buff is executing a turn and its doesn't have a gunner, it won't be firing on you. Once the pilot switches from cockpit to gun, the buff is put into auto-level. Have you ever tried to gun in a buff when the pilot is jinking around ... extremely difficult to keep the pipper on the target.
It's a level buff that scares the crap out of me, not a spinning or turning buff.