98-01: ABS without linked and servo assisted brakes. Older style fairing/windshield with detachable front signal pods. 5" rear wheel with 170/60-17 tire. No electronic cruise. Rear shock preload adjustment with a traditional shock wrench. Brembo calipers. Available in the best colors: Dakar Yellow on the 98-99 and Mandarin Yellow on the 00-01.
02-04: Linked and servo assisted ABS brakes. Newer style windshield/fairing with integrated front signals. 5.5" rear wheel with 180/55-17 tire. Electronic cruise. Rear shock preload adjustment with a knob. BMW calipers. Good colors unavailable.
Mine is a 2001 and I like it best mostly for the fact that it does not have linked/servo electronic brakes, plus it has the sexy Italian Brembo calipers. If you take your bike to the dealer for everything, then I guess it doesn't matter. If you like to do everything yourself (like me) then "less is more", especially when it comes to the extremely complex brakes on the later bikes. You will get arguments either way, but I Iove mine just the way it is.
EDIT: The GT was introduced in 2002 and has the same features as the RS with the addition of more stuff, like saddlebags, larger windshield, etc.