Chris, I had a 97 M600 before getting my 748 and it was a top little machine. Nice handling and really good fun - I did a track day at Cadwell and it was a great laugh.
My only prob was around the 12k mile mark when I was just about to trade it in. It didn't idle very well - it either raced or stalled. It got to the stage when at lights etc I had to really feather the throttle/clutch/brake to keep it idling nicely. Anyway, I thought it was just a bit of an idle speed issue but it later transpired that one of the valves was starting to "leak"
Apart from that the only other issue I had was the main relay (under the seat) blew once and wheels were a bit flakey, but you get that on any machine over time.
If you find the right one go for it. Good luck.
Jacko.