I'd like to see the "boxes" that HTC uses be different sizes for each plane, maybe each "category" of plane. Smaller boxes for those planes that are bigger, or less maneuverable, and bigger as you get to the faster, smaller, more maneuverable planes. This way the odds of being hit in a big slow buff would be pretty good were a fighter darting all over the place would have less of a chance.
Now I think the boxes are all the same size, or are determined by speed/alt, but if there was a way for the game to "ID" the planes and have each assigned a box size I think it would "simulate" the accuracy better.
I think that the box of puffs is just a visual effect. Under the hood AH simply rolls a dice whether there is a hit or not. If the "ḧit roll" depends on the size of the plane, that is an interesting question.
The way I see it, AH puffy ack simulates a volume attack. With heavy acks they were not aiming at any specific plane, but instead fill a volume in the sky that is supposed to have planes in it. In this case, speed, maneuvering flickering the landing lights will not change a thing. The only thing that will help you is being smaller. Being faster will help by getting you out of range faster, but not improve your chances while in the ack volume.
Evasive maneuvers will help only if the crossing time of the ack volume (t_cross = box_size / plane_speed) is similar or shorter than the projectile travel time. So in a akies full of acks (large box_size) evasive maneuvers achieve little more than making your stay in the acks range longer.
All of the above is not true when the heavy flaks are aiming at a specific plane, but I don't think this is what HTC were trying to simulate.
Now, since this is a game and I don't consider the puffy-acks as part of the "simulator" side of it, I wouldn't mind if the hit probabilities against fighters will be artificially decreased and the hit probability against bombers artificially increased.