I use one and can't think of a drawback. With the Scotts unit, you can set it up to absorb sharp hits but keep it light in the corners. The GPR does not differentiate between high and low speed damping. Depending on how it is set up, it can help with very muddy conditions also.
I have a bad shoulder, couple torn rotator cuff tendons. My shoulders and arms take less load. I want to avoid an sharp hits 'cuz I'm at the edge of needing surgery. My 46 yr old body needs all the help it can get!
What else do you need to know?