[ejay]

I would bet here. The reson is that there are a 3 opponents and you have 12 outs to a win. I understand that they may not all call but even if 2/3 call i dont think its a bad deal. This also hides your hand better because when you raise and then check behind it pretty much says that you have a flush draw and and wont get action if you hit it. If you bet and get diamond/2 on the river you still may get callers.