I can't speak to the GPR, but I put a Scott's unit on my son's KX65 last month. When set on the low settings, under normal turning conditions, you can't feel the Scott's unit, but it still stops the big hits from yanking the bars and reduces a lot of head shake. The KX65 was very unstable without it at high speeds. It definately works and he isn't getting worn out from the dampening in turning, even in tight woods. It really seems to have help in the high speed rough stuff, rocks, and 5th-6th gear stability. Not that the damper made a huge difference, but he took 1st and 2nd, respectively, in the last 2 WORCS races. I haven't talked to Scott's about it, because he is happy with the performance, but I was thinking I may have to change the oil in the damper to a lighter weight if it was too stiff even on the lowest settings, but it doesn't appear I need to.