[Danenania]

Do we believe he could have 44? I suppose he could be trying to make you fold 99-KK with the flop raise. If he could have 44, does that mean he could have 33 or 22? How about A5s/A3s/A2s? I suppose that if he didn't have 44 he would have to put you on AK to play anything else this way.

If it's just between 44 and 55 then it's 6 to 3 and you should check/call. If he could have 22 or 33 in addition then it's 6 to 9, but he's much more likely to raise you with 44 than with the others, so you should still check/call. I suppose only if you throw the 12 two pairs in does a checkraise begin to look realistic (I see no benefits to a bet/call). In that case you are looking at a 6 to 21, which is really closer to 12 to 21 since he is very likely 3-betting your raise with 44 (and not with the others, though I don't think you could fold to a 3-bet). It all comes down to discounting possibilities. Do we discount 44 because he opened in MP? Then there's the flop raise. Seems like the two pairs should certainly be discounted for slowplaying the flop and overplaying the turn (though really they should be same as the sets since he can really only put you on AK or AA--still I think most opponents would value them differently anyhow).

After running through them all briefly I believe check/call is the way to go. Quite close though. The kicker is that A2/A3/A5 all seem far fetched to me

If the board pairs is another issue. I think betting will tend to shut down 44, though all the boats of course should raise you. The two pairs should also be shut down by betting except the one that boated up (though a counterfeit two pair would check behind if you check). Just doing some quick math in my head it sounds like betting will be quite a bit better. The only card that you may want to checkraise on is a deuce.

Edit: just changed my mind. I like c/r unimproved now. Don't think I discounted 44 enough. Still like bet/3-betting any card but a deuce on the river though (even moreso now, and maybe on a deuce as well).