Sportcruiser
The MTOW is 600kg no matter what set up you have so usefull load really only depends on how heavy you let your build get. A constant speed prop will be heavier so perversly the simpler less efficent prop gives you more (legal) usable load.
In the real world 110knts seems to be about average best cruise for almost any set up.
We get that with a 3 blade Woodcomp Klassic ground adjustable set for best cruise. I doubt any other set up is getting better than 5 or at most 10 knts better than that.
Pete