Seeing as you have the odds to call on the flop if he all ins and there is hardly any chance of him outdrawing you if he is behind, it's best to check the flop and let him hang himself with nothing and bet the pot on the turn if he checks when he probably has developed a straight draw. If you just bet on the flop, he folds all losers and gets your cash for free if he has a flush.

Of course, if you feel he won't bet without a flush, then check it all the way and hope for a showdown. I haven't played a lot of PLO, but what I have noticed is that decent hands get to see a showdown when they are winning with scary boards ( I've been playing party $25), so you don't have to be as afraid of him bluffing on the river if you check all the way like you would in holdem. Any thoughts?