agressive..
for a few reasons
1. you can take the pot down right there.. about 60 percent of the time thats what will happen. esp if its a low board pretty much everyone else missed the flop.
2. you check your giving your oppents another free card to hit there J or K or whatever then they are not going anywhere and now your down to one card to hit your flush and now they are going to bet into you
3. by betting the flop you are discuising your hand.. so when your flush does come.. you can check it. making them think your afraid of it.. then they will make a huge mistake trying to bluff it. i cant tell you how many times this has happened..
the only time ill slow down on a flush draw is when the board pairs.. its almost sure that a boat is waiting to ride down your flush stream
1. that's true regardless of a flush draw
2. Of course they'll miss their 6-outter the heavy majority of the time and lots of people are more likely to call flop bets with over cards (myself included) figuring that first off that could be just a standard cbet, and secondly that if you do actually have a hand like top pair, betting because you're vulnerable, you could get paid when you hit one of your 6 outs. Implied odds. What happens when your bet gets called and then someone bets into you on the turn when you miss?
3. If you turn it that's fine because then you can bet the river and top pair may call you down. But if you're OOP and turn the flush and check-raise, they're not calling anymore without the flush because you've basically yelled over a loudspeaker "I JUST HIT MY FLUSH"
Anyway, I think betting into it is a valid strategy, personally I like to continue betting when the flush hits, because I think that actually disguises it better. Everyone checks when they hit their monster, so I like betting after the flush as well as before. It makes it look like perhaps I had top pair or something and now I'm hoping they didn't hit the flush, which means they may play back at me as a bluff. I'm just trying to point out that your theory is not perfect (and neither is mine, which is why I mix it up depending on the situation, this is crucial in all aspects of poker, not just flush draws). If you play any scenario one way, observant players will exploit it.