I would say it depends on your size and riding position. I might get the exact years wrong and someone smarter than I can correct me.
98-02 older style and seating position, more forward lean, more crotch rocket; when upgrading my K11RS I decided to wait due to the riding position
03-05, newer version, more relaxed upright position, not nearly as much as the newer ones but better
I have an 04 and love it, thought about upgrading to an 07 plus but decided I like mine too much and don't want the hassle
I suggest you find some place to check riding position on the various years and see which works best for you