I don't doubt that performance increases with the right prop and with a folding or feathering prop.
What I would like to know is specific examples of improvement. I am not talking about comparing a fouled crappy fixed against a brand new folding or feathering... but between a clean properly sized fixed and a folding or feathering.
My fixed 2 blade
backs well "enough" considering I don't back very much. What it will do is pull the boat's tern over nicely for docking
and I can use it to get some way on when backing out of a slip once a year or so... I stay on moorings or anchor
so the back is for getting out of winter storage
. My 18" fixed 2 blade
pushes me at hull speed
well before the "red line" and when sailing stands straight up aligned with the keel so it's profile is quite small.
I can't imagine how much improvement I could get out of an "upgrade" to folding or fixed,yet I have heard others say they simply could not back down until they installed a MaxpProp.