'99-'02 the same, '03-06 the same.
The '03 on got a high flow head =more power, a hydraulic clutch and dual discs, some better bearings and an extra oil nozzel in the engine. There is probably more but not what I remember. Buy an old one , set it up right and buy spare parts to travel with. The basic bikes are the same. Add a steering stabilizer. You will be happy and still save money. Buy good riding gear and a new helmet. Get good bags. It's the set up, not the bike. IMHO.
Bill in Tomahawk, WI.