Puck you seem to have misunderstood - I mean the explosive puffy ack, the short range small caliber ack is no problem.
"Players that indefinitely re-up" - Beside the point.
"(Thou shalt not be permitted to hide in thine own ack)" - Not what I'm talking about.
"but I'd advise staying away from areas with enemy ack, cuz it's mean." - That's the point, you can't stay out of it except by diving below 3kft, flying away from it (and hope you somehow don't get hit, no matter how much you dodge - "There is some reality for you"; bombers did it IRL), or with some luck have some other poor bastage pick up the flak's attention.
Once you're in its reach, it'll hit you across mountains, regardless of whether you are moving faster than its aim could possibly keep up with if it obeyed the laws of physics. Not modeling actual ballistics for cpu budget is fine, but it should at least have a compromise like I suggested.
Once again if it was anything like I suggested, planes flying a predictable trajectory would get hit at least as well as they do now, while planes that don't would stay out of the effective volume of the "box".
