My two cents worth says i did not feel the 15 horsepower difference. hardly noticeable, i would say. Both machines were low seats, (i am 6 ft 2 inch), and felt the 800 set up better for me. Crazy to put cast wheels on a dirt bike, brakes a bit soft, but other than that, F650 surprised me favorably. I will still pick up my f800 in 3 weeks, can'