This has been a big topic and yes, sanded hull is faster. Even a few of the big racing cats do it and now they have dimples like a golf ball in some areas. I have some video of CRC offshore cat with this. Also, the big hydros do this with a matt surface on the sponson hulls.

It is about how the water release from the surface. Slick keeps a sheet of water on the hull. It is true and this has been proven.