OK, well here's my take on the hand...
On the flop, my hand is very likely to be winning here, I want to pressure anyone with two small pairs or a pair of aces (if that's what PFR had) to fold, and obviously I have ten outs to the nuts even if I get called by a better hand. The guy calling me looks liable to have a straight draw, given the read on him and his play so far, which would be ideal as we're probably drawing to the same outs so I'll win if we both miss.
Turn means I no longer have an overpair, but I like my bet here a lot. If he has a variety of straight drawing hands my KK will still be ahead, and although it's very possible he has an ace there's certainly no reason to believe that's the case. I think a set is unlikely given the fact he's checked both streets, and the flush draw gives me the backup I need to ensure that I'm not making a big error here by betting - I'm likely on a minimum of 15-odd outs against any likely hand, and i'm actually favourite against two low pairs if ALL my outs are totally live. It also puts pressure on him to perhaps make him fold a live hand (or even drop a hand like 9TAx, which would be a huge coup for me as he's currently winning).
However, his check-raise is then perplexing. At the time I thought he'd likely ultra-slow-played a set (fairly unlikely) or perhaps caught top two to go along with a flopped draw of some sort (also not THAT likely but out of the possibilities, probably the most likely holding). This is where I went wrong, though - it's also very possible he's made a huge draw here and is pushing it hard, there are a lot of draws out now. Even though this seems a very unlikely way to play it's certainly more than possible, and considering the other seemingly unlikely alternatives, and the fact he's played this hand in an odd way, it has to be more than a consideration.
Given that I'm probably ~40% equity (maybe a tiny bit lower) against a range of hands that he could play this way and that beat me (top two plus a draw, a set, big draw plus ace) obviously I have to play here. However, if we factor in the chance that he has a hand that I'm ahead of here (a big wrap that's now turned into an added flush draw being the most likely candidate) it's clear that I can't let go of this hand with so much money in the pot; even if he only has a drawing hand maybe 10% of the time, given the fact I'll catch a winner against him on roughly 40% of rivers, I'm in reasonable shape to set my last 40 bucks in either now or on the river regardless of what falls - and, because he might fold a totally whiffed draw or a hand like two small pair if the river brings a flush or straight for me, I figure I'm best to stick it in on the turn.
Basically, it's a situation where my favourite omaha commandment (don't worry about making small equity mistakes too much when it's a marginal spot, but avoid making huge equity errors or risking making them without a very good reason). Here, if I'm ahead and I let go of the hand, that's a collosal error. If I set my last $40 in when I'm maybe 40-45% equity against his likely range for making this play (and thus will end up losing 5 bucks or something tiny by making that play) I cannot be making anything other than a very, very small equity error. If I call the raise, whiff on the river, then muck my hand and pat myself on the back for making a disciplined fold, that 10% of the time (based on my estimate - I guess it could even be more) that he's on a pure draw or a two pair that I beat by pairing low on the river, I've made a collosal mistake that has cost me more than a full buy-in.
So given this reasoning it would've been correct for me to push the turn, even though I couldn't beat top pair, with a hand that very, very rarely would be ahead, but that would hold a likely 40%+ equity against his range of hands for making this play. I messed this hand up from an equity perspective; if I play it this way 100 times I'll maybe only lose by getting bluffed off the best hand a couple of times, but those times will be very costly.
Results:
I fold to his queen high
. Of course he won't have this hand (a big wrap plus Q high flush draw on turn) very often, but this time he did and I had to suck it up.
Monk