There's a massive difference in the "feel" of the bike, power aside. 0-100 specs are similar, sure, but turn-in through corners is vastly different.
In my experience, with the supersports, it has to do with rake angle and the length of the bike:
Triumph (daytona 675), KTM.. feels like they have EXTREMELY steep rake... So the bike almost wants to fall over on itself when you turn slowly. Some people really like this... If you're very skilled, or riding only on smooth track-like surfaces, it's fantastic. But if you hit a bump mid-corner on the street... not so much. Some of this can be fixed with steering dampers for street use. Overall they feel twitchy.
While my Street Triple R does like to fall into corners, it's never done it in a way to scare me, rather it's very enjoyable to see a corner, think about turning, and the bike simply following my thoughts. That said, I do agree that I have hit some bumps in the corner that have frightened me a bit.
Regarding 600 vs 1000. Keep in mind that I am a huge proponent of learning to ride on 500cc bikes, 650 twin max, then moving up to a liter twin non-supersport before buying ANY supersport bike.
Agreed. Putting 1000mi/month on my GS500 and learning to ride well so as to keep up with 600cc & 1,000cc supersports was invaluable.
But, in the 'how easy to ride' discussion, liter supersports are much better and safer than 600. 600cc powerbands start out dead.. 2000rpm, 3000, 4000, no power.. Then, all the sudden at 5000-6000rpm you get 100hp almost instantly. It's the perfect recipes for wrecking mid corner trying to learn throttle control.
Another reason I love the Street Triple. The torque and HP curves are almost straight and there's no unpredictability in the power. Probably one reason why they haven't really changed the motor in almost 6 years.
literbikes have much more predictable power... 2000, 3000rpm, you have 60hp, 4000rpm 70hp, 5000rpm 90hp, 6000rpm 100hp... It's just easier to gradually get on the throttle, particularly if you want or need to go fast.