Robin,
I had a CBR600 FX which is the one you are considering, last of the carb CBRs, I fitted a Scorpion cand and a matched Dynojet kit and put 16000 miles on it in the 2 years I owned it.
Not a single problem and it was run all year round including French trips, trackdays and regular runs into Wales.
It would be my 1st choice as an "everyday" sportsbike if I needed one.
Heres one for sale on VD as a comparable and this ones not badly priced ...
http://www.visordown.com/forums/showthread.php?t=218512