Lots of back and forth with the end result always shoving the good'ol XR600r into a trash can when compared to the 650.....Cripes, Will the 650 be a piece of junk if a 660 becomes available? The 650 does have a couple technological improvements and yeah, its got a slightly larger displacement, but they are both most excellent big red pigs that can plow fields with thier monster torque.
If I do decide to grab a 650 [lookin' at one now] ,then I'll still keep the 600 , and if the CRFx6 becomes a reality, then I'll have 3 bikes...... The 600 made many soil thier trousers when it debuted, .....still a mint ride too. Always hear the 'my dog's bigger than your dog' with these bike owners at the same parts counter... I'm sure that the mods on my 600 and the big bore displacement [that makes it a hair bigger than the 650] would make a few 650 owners milk thier pants..... Both are proven and are a blast as long as we can get parts for them