When I was about 15-16 yrs old we had a 185s and my uncle had a 200x. They were both only a few years old and were in a good state of maintenance. I think that the 200x was stock, and our 185s had a K&N and a Supertrapp. I weighed about 155 lbs, and my uncle was about 190 lbs. From what I recall, it was close, but he could just edge me in a drag race. As far as top speed is concerned, I can clearly recall one time when we were out on dirt roads with miles of open road and I rolled on the throttle in 5th, and he pinned it also. It was dead even at top speed, and I mean stalemate. Then I tucked down and put my left arm behind my back and pulled my knees in tight and just started to inch away from him. He replicated my position and then we were even again, but I held the number of Feet I had gained by aerodynamic advantage and he couldn't close on me.

However, when I rode his 200x, and it didn't have to carry around the extra 35 lbs, it felt noticeably quicker than our 185s when running up through the gears. So all other factors being equal, the 200x should have a clear edge.