[adouglas]

I agree with the boss man (except for the "clip ons below the height of the seat" bit... they're low, but not THAT low).

A step-up sport bike, vs. a true supersport, is what you're looking for. 600s are supersports.

Assuming you're looking for the same style of bike, i.e., a fully-faired machine. If you go half-faired or naked, the field opens up considerably (if I were to buy a naked right this second, it'd be a Yamaha MT-07, aka the FZ-07 prior to this year... rode one at a demo day and loved it).

So in current bikes the Ninja 650, Honda CBR650F and Honda CBR500R come to mind.

Older bikes that are now discontinued include the Suzuki SV650SF, Suzuki GSX650F, Yamaha FZ6R, and the Kawasaki Ninja 500 or EX500 (similar to your pregen but bigger). The Honda CBR600F4i is a bit closer to a supersport but is fairly mild.

Of all of those older bikes, the SV650SF is my favorite. It's identical to the SV650 but fully dressed. That V-twin motor is terrific... torquey and good power for the street.

The GS650F is what used to be called the Katana back in the day. Kind of heavy, unremarkable. Rare. But it superficially like a GSXR so projects a "racier" image.

The FZ6R is also rather heavy, but is built around a detuned YZF-R6 supersport engine so it's got solid underpinnings.

The Ninja 500/EX500 is a bike I used to own. It has its shortcomings (I never did like the seat at all, and ridden hard it can be a bit flexy) but it's a nice blend of power and weight. Technically it's half-faired, but you usually see them with chin fairings so it comes across as fully faired.

The CBR600F4i was on my consideration list but I've never ridden one. Has a good rep as a "gentleman's sport bike" that isn't as hard-core as some.