Not sure what to make out of that either, slipping the clutch to get it into the lower rpm's makes no sense..why would you have to slip the clutch to get it into the lower rpms..i could see slipping it to get it into the high rpms..honestly i have never had an issue with my 02 220, nor my 97 200..i havent heard of any major clutch issues with these bikes ever. i would go look at it and at least ride it, sounds like a clean bike, who knows maybe the clutch cable is adjusted wrong at the perch..haha, people do that all the time, they'll adjust the cable at the perch way out of whack and think the have a clutch plate issuse cause it'll jump out of gear..go look at the bike and ride it, the kdx's do have a bit of noise coming from the clutch side, that's why most reccomend running a little more gear oil to quite it down. These bikes are the best ever made, you gotta get one and experience it!!! sorry i couldnt be more help, the best thing in my opinion is just go look at it and see for your self.
Ryan