I still think more weight should be given to how critical the damage is, not by the amount. As I said, you could tear up the fuselage of some aircraft and the guy might not even notice. Then someone else comes along, inflicts his "30% for an assist" that tears the wing off (Jugs and IL2s are good examples of this). I see the "official" stance as it is now, but who do YOU think deserves the kill? The guy who inflicted the most, but effectively meaningless, damage, or the one who may not have torn up as much of the plane, but put his shots in the right spot to cause the most critical damage?
That'd be a GOOD way to put a stop to the guys racing to fill a falling enemy with holes as he's spiraling wingless to his doom.