How far do you go when drawing to straigh flush?

[beekeeper]

A really interesting hand developed last night in our local game. Thankfully, I was not in it, so I had the pleasure of watching it.

The betting was average preflop, but on the flop it intensified until 2 players were all in. When they flipped their cards the small blind, with 2d4d, had a flush (3 small diamonds on the flop) and the big blind had 2 pair. The turn gave the bb a full house, and the river gave the sb a straight flush!

The first time I played in a casino, my first hand, I had 7c8c in the bb. The flop was 6c9cA. The betting was aggressive and I called to the turn, which was not a club, and I let the hand go when the betting started, figuring the price would get too high to chase.

I was just wondering, does the strength and potential payoff of a straight flush change how far one should be willing to go to pursue it? Does it make a difference if it's open-ended or gut shot? Especially when your flush otherwise would be a little flush, how would you play it when the betting is aggressive and/or it's a multiway pot?