Can’t help with the freewheel decision as I ordered my 125mm schlumpf hub without.
My foray into freewheel was to build a 20” freewheel unicycle with a Madazz hub. It has a brake disc but no calliper yet. I played around with it on gentle grass slopes. If I get keen on free wheeling, I’ll get a dedicated unicycle for it. Mad4one Flick Flocks are currently sold out.
With the schlumpf hub not having function to disengage the freewheel…yet, it is not for me.
My intended use for schumpf hub is for commuting - there are hills that I can manage with 150mm crank, and then I would like a bit more speed on the flats. I’m finding that shorter cranks don’t suit me.