HiTech, how often does AAA check its aim, and adjust if needed?
IMO, 5-10 second would be a good delay setting. It would allow evasive manuvers to be effective (since ack-bursts are just 'spawned' around you, there is no delay between firing and arival at target), it wouldn't require you to be pulling hard turns in bombers, but it wouldn't let you just alter your course slightly, and continue on your merry way as the ack bursts off to your left.