I had a Gori propeller
on my Jeanneau
49DS and loved the system. If I wanted to motorsail or motor
in settled conditions I'd get the prop into "overdrive" mode and run at much lower engine revs for the same speed. This really gives enormous fuel savings when motorsailing.
The downside is that it is possible to overheat the engine when in overdrive. I did this once by mistake when I was trying to get to Falmouth Harbour in Antigua
before dark. I decided to install what all trucks have - an engine gas exhaust
temperature gauge. This would let me run the Gori in overdrive mode and use the exhaust
gas temperature to get the perfect load factor. I had the system spec'd out from VDO but then ended up selling the boat. I still have my page about the Gori at https://www.sv-zanshin.com/zanshini/zanshinigori.php
My next boat already had a folding propeller
system, otherwise I would have immediately gotten another Gori.