I think this is a good hand to check back on this flop.  We don't get many better hands to fold, or worse to call.  We also don't need a ton of protection, as the hands that fold to our c-bet don't have much equity anyway.  Also, if we check back flop and he leads on the turn, we can almost always continue, either by calling or raising.

As played, it's a weird spot.  The hands that he is repping are mostly QJ+dd, but for him to x/r on flop (and again on turn) this deep, I think they have to be mostly AQJ or QJ9 + dd, or sometimes KQJ+dd if he's on a looser side.  Thing is, I'd expect him to 3b most of these hands preflop against your wide-ish range.

Then again, he might have just flatted those.  We don't know for sure.  And it'd be a bit disastrous to get 300bb in with what can be like a 40% equity hand.  That said, my plan would be calling turn and any blank rivers, and folding on diamond rivers.  If he checks on diamonds or board-pairing rivers, I might elect to bluff depending on situations.  If he jams on the board-pairing rivers, I think I have to call because he's not repping boats very well, unless they are KKQJ or stuff like that, specifically.

River is a gross spot but I think we have to fold.  We almost never scoop the pot, while he can frequently do so.  If we call and chop, we win ~$250; if we call and lose, we lose $325.75.  We have to be chopping this about 57% of the time, and I just don't think that's the case here.

Thx midori! Your analysis is spot on IMO, i was planning on possibly shoving a non diamond board pair on the river if he checked to me.   BTW Im no midstakes PLO expert by any means but I think alot of players on this site are rarely 3betting pf with non AA hands.   Thanks for the insight