I guess I don't really understand why, if sport handling, quickness, speed, and lower weight is such a high priority a street motorcycle isn't purchased. Put a top case/panniers on it and you have storage always in place, if that is a consideration. What am I missing?
For those people, it's the Aprilia MANA. A scooter, to me, spells "Practicality." Take away any of that practicality, but charge the same price? No way. If I wanted acceleration and handling above all, I'd be looking at a MOTORCYCLE (and I have one of those too). The TMAX was "nice," but the Beemers are better. They require lower octane fuel (89 vs 91), get better mileage, and have more range because of that AND a higher fuel capacity. The Beemers also have the electrical system to handle heated grips, seat AND electric clothing, something I know from experience the TMAX can't get close to handling.
Having ridden both the C650GT and the TMAX almost back-to-back, saying the TMAX is "faster" or "better handling" is splitting hairs. The difference is not that great; it'd be like choosing between a high-end Lamborghini or a high-end Ferrari. In the hands of a decent rider, either scooter will leave many a squid gawking as the scooter's tail lights disappear around the bend in front of them.
Both BMWs also give the rider more options for leg positions, and provide more leg room than the TMAX. And, of course, there is the choice of a locking glove box (though for all I know Yamaha addressed that shortcoming in the new model).
But not EVERYTHING goes in the Beemer's favor. The TMAX does have much better rear-view mirrors. All the better to warn their owners when to move over because there is a 650 scooter breathing down their necks and anxious to get past...