Re: AKo vs. a limper-reraiser
 

I'm going to have to think about this hand some more, but I think it is WAY more likely to see a limp re-raise with AA than it is with KK or AKs even though I have seen it with those other hands also.

Also, given that you 3-bet the flop and an A hit, doesn't his subsequent 3 bet on the flop lower the probability that he has KK.

Finally, his aggressiveness on the turn could indicate he did have KK for a STR8 (though I still doubt it).

I think I would have backed off on the river for sure.