FZ6 looks a very safe transition from a FZS600 Fazer. Infact looks similar to the fractionally newer Mk2 facelift FZS600.Just a revised design plus obviously newer technology, being a few years newer (2004+).Have you considered a FZ1 or MT07/09? A more substantial "upgrade", otherwise I'd just keep the FZS600
Depends where he lives, it's no good for the ULEZ charge in London for example. £12.50 a DAY just to ride it.