Plain beam array: 89%
Acc2 beam array: 93%
Plain beam array: 69%
Acc2 beam array: 69%
I cannot reproduce anything to emulate these results internally. I'm unable to track down any individual variable that could be the cause of this discrepancy, based on all of those that I have the direct ability to manipulate. No matter what method I use to increase my test character's Accuracy or the Defense of the opponent, the results are always exactly as expected.
I've requested additional debug support from Programming, but I can't promise that they'll have time to assist in this endeavor.