I have a LY6 and run the 5 blade prop from OJ (2009 X45). When we surf we have all stock tanks full, 2X 750 rear lockers full, 2X300 front lockers full, 2 X 400lbs sacs under port seats, and 1200lbs sac on port side floor. at 10.8 mph I am turning 4100 rpms. Wake is really nice. Prop hauls the boat up nicely. I am happy with the higher RPMs as the motor is not working as hard. We had 10 people in the boat with all the ballast and RPMs went to 4500 to hold the speed. The wake was massive but the boat was slammed to a point I was not comfortable with.
I do however hit the rev limiter at about 34mph empty. Wake board RPMs are about 4300 at 24mph. This prop really holds the speed nicely especially when loaded heavy. I am very happy.
I don't track fuel usage so I cant comment.