[Heisenb3rg]

Because you have his range reverse dominated when ahead, but your equity isnt that great this is a spot I like to c/c, since you want to let hands like AQ see as many cards as possible.

If you think he wouldnt call down with a hand like AQ or 88 (without a diamond or if the diamond misses) then playing this hand passive from the start is clearly the best play.

If you think he'll pay you off really light if a diamond doesnt fall, you can play it either agressivly or passivly, both should yield a similar profit.

Without a read id play it passivly.. Lead out if you hit a 9.

The only reason I think its clearly better to play agressivly is if you tihnk he wont raise bluff this turn very often, so you can fold this to a turn raise.. If he's agressive enough that you have to pay off his turn raise (yet dont like it).. Just play it passivly.

Most opponets you can probabily fold once he raises the turn, but I dont recommend it as a habit to get into, since against others its a huge mistake.

Conclusion:
Predictable showdown monkey = c/r flop
Fairly agressive showdown monkey = indiffernet
Super agressive showdown monkey = c/r flop (since his PF raising habits imply hes got a lot of hands to rebluff you with, but your equity is much better).
everything else = c/c flop