[kurto]

"OP: Semi-bluffs are of questionable validity in lower stakes games,"

I don't think this is true. There are a lot of good reasons that the semibluff is an important tool, even at the lower stakes games.

(1) It is wrong to assume all players don't pay attention at the lowerstakes games. Semi-bluffing is one tool to keep opponents from putting a read on you. This may not be AS important as at a table with good players, but it is still a useful tool nevertheless.
(2) related to one: It disguises your hand. Which is easier to play against? Someone who only bets when they have something or someone who bets BOTH when they have something and when they have draws?
(3) Oftentimes... betting will take the pot. You will take many pots you would have had little chance to win without betting.
(4) Building a pot. If you have 5 passive limpers in a pot and you have a nut flush draw... you may not get paid off one you make your flush. But your odds are correct if they'll all call your draw.
(5) Superdraws-- statistically, you may have the best hand with 2 cards to come. Get the money in while you're ahead.

I may be missing some but I think that hits a lot of the big points.