I assume you'll call down the last $150 so you might as well bet it.

Possibilities:

a) He has a low boat made with 99, Q2 or 22, in which case he'll presumably pay off. Equally, he might have trips, something like TJQK would be a possible hand given the action.

b) he has a higher boat (AA or AQ) and would push the river anyhow.

c) he has a draw of some kind. In this instance you *may* miss a chance to snap off a bluff on the end by not checking but he'll have to be a pretty dreadful player to call your turn CR without a boat or set of some kind so this seems a *very* unlikely possibility.

d) he has Q9 and is going to split.

So, take your pick as to which is the most likely. I'd say if he has a hand that beats you you're liable to call anyhow, and there's plenty of hands that the average player will call on the river that you beat, so I like betting. If you think he's tight enough to drop a hand like KQ to a full bet you might take a little heat off and only put in $70 or so, though that may mean you get paid less if he has 99 or Q2. In any case, I'm not folding OOP here.