I have a marlin with F225's. I am using Enertia 15 X15P and they are outstanding. WOT is right at 6000.
The boat rides extremely well with them.
Yesterday I was cruising at 22kts getting 1.7mpg. Generally I cruise about 24 or so getting 1.4-1.5
I had those 17P props. I tried the 15P enertia and fell in love based on a friends recommendation
You may turn slightly faster rpms but gph is reduced. The motors actually sound completely different, like they aren't working as hard.