I would buy a new bike when my SV dosnt do what I need it to. Currently, I'm thinking of getting a second bike as a better trans-london commuter, something upright, something fuel injected. Maybe a pointy naked SV
Mind you, its only a thought. I dont have the money, and having two SV's would be pretty silly, I'd be better off getting somerhing completly differant so I can still enojoy the 650s for what it is (a sporty machine) and get something really not sporty (CBF500 stares at me for this)
Of course, one day I will have to buy a honda SP2.
Matt