[gharp]

I'm pretty far from being a "math guru" but I'll give this a shot.

Let's assume the hands for villain are:
30% of the time = 4 or 8 (15/15)
25% of the time = flush draw
45% of the time = paired the board (5% on the A, 40% 7,6,5)

Also assume:
- he'll bet/raise with the made str or flush 100%
- he'll bluff with the 4 25% after seeing you check, and always fold if you bet
- he'll call 100% with a lower pair
- he'll bet 50% of the time with a lower pair or the A

SO...I think you can calculate your expectation as:

Bet+Fold = .4(1) - .4(1) - .05(1) = -.05 [calls w/low pr; raises w/str; calls w/A]

Check+Call = .25(.15(1)) - .4(1) + .5(.4(1)) - .5(.05(1)) = -.1875 [bluffs w/missed str; bets w/str or flush; bets w/low pr; bets w/A]

With those assumptions (which might suck), it looks like Bet+Fold is the better play.