Its really a matter of what you prefer and the intended usage. Sure a 600 has a lot more tractable power than they did just a few years ago and will be easier to throw around in traffic. By the same token you can get into some dumb ass situations throwing a 600 around and there is really nothing quite like the feel of a liter bike either working trough the gears or powering out of a curve with the frnt starting to lift and the rear starting to slide.

Agreed completely on the insurance and price deal, as for model year, newer is always better, they learn things on the track and develop new materials and manufacturing techniques that allow smaller compact pwr units as well as always decreasing the rotational center of mass etc. And on a 600 although the peak HP and TRQ numbers may be close, the advances in power usability will be HUUGGEE.