Kitfox2009,
I agree, a ground adjustable prop on the whole will be no where near as efficient as an IFA one. However, there is a large variation in the efficiency of different ground adjustable props. I went from a GSC to a Kiev and I was utterly amazed at the difference. The GSC didn't run that smoothly, was noisy and performed around 20% worse in the climb and cruise. It seemed rigid and unforgiving.
I would strongly urge anybody who is considering an IFA to try a Kiev 263 before they spend their money. The smoothness is incredible and you will be amazed at the acceleration!!!!!!!!!