Hey there,
I have a '97 and an'01 KX. I prefer the '01 rear suspension as it has a High Speed Compression Dampening adjuster, where the '97 does not. This allows you some control of ride height AT SPEED. Also the spring rate is better for me on the '01 (5.2kg\mm) vs. '97 (4.8kg\mm) as I am short and light. The stiffer spring allows me to run 110mm of "race" sag, and maintiain a 30mm static sag. The sag "thing" works! I feel like the bike is more stable at speed and plush without the back tire hitting the fender (I am not smooth lol). However, obviously the front suspension has alot to do with it. Additionally, so does the subframe, as it does effect rider position. I find I ride the front of my '01, where on my '97 I weight the rear more. Well, that's my $.02. Hope this helps. Oh yeah... I also have a longer link on the '01, so the rear is lower.