Walt makes some good points. Most "high thrust" props have elephant ear blades to push more water, and are also larger diameter. This would certainly help with reversing, as it can throw more water. I had never thought that the elephant ear blades being symmetrically shaped would equate to more equivalent thrust forward and in reverse, but that makes sense to me.
Also, think of the prop as a wood screw trying to get through water. As the prop spins, it wants to move forward it's given length (based on the pitch.) This equates to a given speed at given RPM. Now, if you take that prop which wants to go fast (move forward more per rev,) because it's got a bigger pitch for a planing hull, and you prevent it moving it's distance and speed because it's on a displacement hull, it will have far more slip and be less efficient. And will probably prevent the motor turning fast enough to get into proper RPM territory.