What exactly is the point of running the spool off-road? The bumpier the road, the more you want some slip tolerance in the spur. If you’re just trying to go fast, the smoother road, the better.
I do almost exclusively off-road bash/racing with a 3s blx granite. I never race with 100% power, because the wheels spin out, and the loss of control is no where near a good trade off for the slightly higher speed.
The only scenario I can imagine wanting an off-road spool is at the salt flats where everything is flat and smooth and traction is lower than street (so the wheels spin easier than the gears stripping).