I have to agree with Frisco. The FZ would be the better choice in the long run.
The 600R is a great bike, and has been grossly overlooked for a long time, but the FZ is current technology and should be around for a while. For 2008, the 600R has been dropped from the lineup, so the support for it (accessories, AM stuff, etc) will slowly fade off.
There are a ton of very happy SV 650 riders out there, and from what I've seen, much more aftermarket support. The bandit is old school UJM, and the Katana has just never really been that good a bike. Not that bad, I mean they don't fail regularly as I recall, but just about every aspect of it will need improvement once the rider's skills develop.
My $0.02