Benefits>Costs when it comes to AKP. What he delivers for us in attack far outweighs any additional defensive deficiencies he might still be carrying from his tits days. That first try he scored against parra, who else in the comp can score that? Absolute sky is the limit with what we can do with him on attack.
Back in the pre-Webby era, I think I'd be more concerned with someone like an AKP coming into a side that already couldn't defend. But now with the solid defensive foundations we have, I think we can afford to carry one high speed/low power winger. Especially if we have power elsewhere in the backline (ie RTS, DWZ and potentially CNK if he comes back in).
Having speed has never been more important. The new ruck interpretations in the game clearly have benefitted the faster teams as opposed to the slower defensive oriented teams. I think the improvement in the cows and manly in recent times has as much to do with that as opposed to any genius coaching by Payten/Foran.