Image and changing gears

I'm not sure if this is the right forum or not, so if it isn't just point me in the right direction. Anyway I was wondering about image plays and balancing them against your "standard" game. Are image plays really only worthwhile at say 3/6 and above? It seems that at 1/2 and 2/4 (against non-regular opponents) one could seemingly get away overbetting only the nuts (ie. never overbet bluffing) and still get paid off regularly by people looking you up. For that example (overbet nuts vs overbet bluff) it seems that at lower stakes I'm getting called almost far too often to make such plays with bluffs correct.

The reason I'm wondering is that I've been playing a lot of 3/6 lately (as well as 2/4) and I feel that I'm extracting more value at 2/4 that at 3/6 for similar hands. So is there really that big a difference? (this is over about 15k hands so I'm sure some of it is just ST variance)