"Most people seem to think that because they get more revs using an APC then they must be better. What it really means is that, for one reason or another, the APC isn't as good at converting HP into thrust."

I don't believe we can draw that conclusion without more evidence. Why couldn't it be that brand X prop gets more RPM because it has less drag? That would actually make it more efficient in converting HP into thrust. You have a point that measured pitch and disk image can make comparing two identically marked props (i.e. two 10x6 props, etc.) difficult, but I don’t think you can conclude that the faster a prop spins, the lower the efficiency.

Cheers.