More on draws

[Laughingboy]

I've seen a couple of conversations about playing draws lately, but none seem to fully address my question: In a NL SNG, assuming you have the odds to call with a draw, when should you take off a card? In a side game, the answer is "always," (assuming no pair on board, yadda yadda) but what adjustments do you make in a tourney?

For example, last night on Stars with 150 blinds I had AhKh. The flop comes down two little hearts and a Qs. The pot is 1800 chips (I raised to 450 on the button and got 3 callers). I have 1500 chips left. The SB, who also has 1500 left, bets 300, folded to me. Now clearly he's giving me the odds to draw at my flush, but what else should I be thinking about? Note that I don't care so much what the answer in this particular case is. Rather, I want to know how to account for other considerations like increased chip value as your stack shrinks, etc.

In this case, Let's assume I put him on a pair of queens. How much would his bet have to be for it to be correct for me to fold, and why?

Thanks in advance!
Sean