I have one. Pro's lets the motor slide on gravel shoals keeping the skeg from digging into bottom. Does deflect some gravel from going thru prop. Con's drastically reduces efficiency of prop. Causes disturbance of water flow cavitation. does NOT protect prop from rock strike. First day I had it broke blade off 4 blade solas very upset at that one. River runner caused motor to turn catching blade on rock side of down stroke. Moss hangs up more easily in motor. Acts as shovel if trying to lift motor out of mud, sand, moss etc... Catches branches between prop and guard.
I would not buy another and take it off most of the time. Go slow. I think jack plate would be better investment to raise motor.