[DpR]

Well, he cant have the nuts, so it is tough to put together how we are thinking the same player who cannot 3 bet the turn with a set can 5 bet the turn w/o the nuts. Also, if he does have a set and he fills up, the turn 4 bet will perhaps get us pretty sick action on the river.

I think it is rather unlikely we can be 5 bet here, so in sticking with the title of the thread as defined by OP, I prefer a FSD 4 bet. We also get to win an extra bet when we fill up since is possible villian will check the river if the board pairs.