[DrunkHamster]

Alright, I'm going to have a go at doing the numbers for this. The fact its a 3 flush makes it harder by far, but nevertheless I'll try.

OK, first off, lets look at raising the flop. There are already 6 SB in the pot. Lets assume we are behind. We raise, then call down a 3 bet, losing us 7SB. If we are ahead, and we raise, we can hopefully assume villain will call the raise, then fold the turn or river. We gain, say on average 4 more SB off of him, making this +10SB. So, we have to look at the combinations of hands he has. AA,KK,AK,AQ we lose to. QQ,JJ,TT,99,KQ,KJ we beat (for a fairly loose raiser this sounds about right.) So there are 1 combination of AA, 3 of KK, 6 of AK, 12 of AQ = 21 we lose to. 6 of QQ, 1 of JJ, 6 of TT, 6 of 99, 12 of KQ, 8 of KJ =39 we win. So, on average, we make (39*10 - 21*7)/60 = 4.05 SB
Remember, this is assuming a relatively high raising range AND assuming villain calls the turn when he is beat.

OK, so now lets assume we just call down the whole way. The pot is 6SB at the flop. If he is ahead, we lose 5 SB. If he is behind, we win 11SB (this is assuming a bet gets put in at the river, which would happen if villain checks behind). So, using the same combinations, the EV is (39*11 - 21*5)/60= 5.4 SB, making this more profitable, even allowing for the times villain has a spade, and another falls (lets say he has one on average a third the time, and another will come around a third, so we lose 1/9 of 5.4, making our average EV 4.8 SB, still better.)

Now this may be completely wrong, but I'd really appreciate some of you critiquing it. If anything, I've screwed up the combinations.