Hey! Thanks for the post. As I typed my earlier response I had considered the potential for a change in friction dynamic, but I wouldn't have guessed plus or minus for fresh versus salt. I know she'll draw a bit more. Good info...
I've found that you lose nothing when getting into the Great Lakes with a yacht from salt water as far as RPM's go on planing yachts with electronic engines. Yes there's less bouyancy, but also much colder water and air temps. So the aftercoolers are more efficient and air denser, so from what i've seen it tends to be a wash. Certain boats may differ.