Welcome! You didn't say, but is your current bike a V-twin? The 600 sportbikes will run 130 mph all day with no problems, so highway speeds are nothing for them. Most of the 600's will hit 60-70 mph in 1st gear. Mine tops out right at 65. If you're giong to commute on it, definitely consider some alternatives like the Ninja 650, the Suzukui SV650S, and the Yamaha FZ6R. If you like the standard look, there are all kinds of alternatives, especially if you're willing to buy used - Yamaha FZ6, Kawasaki Versys and ER6N, Honda CBF600, Suzuki V-Strom, etc. Any of these bikes will run circles around a 750 cruiser.
"We didn't trade shoves; I did all the shoving." -Bobby Knight, 1981