I am on both sides of this one...
I get a lot of free kills, and I give a lot of guys kills while stripping ack.
I do a lot of jabo/de-ack sorties and usually die before I finish the job. I have never had a problem with the enemy plane/pilot getting credit for an ack kill on me. His presence often pressures me to de-ack quicker and to take bigger risks. Just because he didn't get a hit on me doesn't mean that he didn't play a big part in getting me killed. Besides, I don't think that the current system gives you perk or score points for maneuver or ack/freebie kills.
Either way, no way should the ack get credit if it did more damage. Even if you blew a guys wing off as he entered ack range I think the ack would often still end up doing more damage and end up stealing the kill.
I like the current system even though my score would probably benefit from the suggested change.
eskimo