The march 2012 issue of Rider magazine has a brief review of both the BMW C650 GT and the C600 Sport.
Although you may think engine sizes are different, they're not. It's all about the buyer's perception. Both scooters utilize a laid down 647cc parallel twin with four-valves, DOHC, FI, counterbalanced and running through a CVT transmission.
15-inch wheels with triple disc brakes and ABS are standard on both scooters. The GT does get BMW's electrically adjustable windscreen while the Sport is strictly DIY.
Both machines will be sold in the US in 2012 but pricing and exactly when have not yet been set. It's a BMW, but with the 650 GT going head-to-head with the Suzuki Burgman, Honda Silver Wing and Yamaha Tmax, I'm personally expecting a similar price to lure buyers away from the Japanese marks. A few months will tell.
Quite a long way from my '62 Vespa GS and it's 4-speed 160cc single.
Monte