New owner (and new poster) here but I don't pick it up 'til the morning - I will update with reviews.
I rode both the Sport and GT before making my decision, and I think I actually liked the ride of the Sport a wee bit better as I'm used to a stiffer suspension from my Sprint ST, but it probably just needs a little more preload for my fat rear, and I think I'm in the minority in this respect. In the end, I could not give up the better looks (IMHO) and more importantly immense storage of the GT.
In the meantime, they're actually doing a series on the GT over at webBikeWorld, having purchased one and planning to use it as a long term tester and documenting upgrades, etc. - check it out.
EDIT: As far as first impressions go, it has more power and more secure and stable handling than other scooters, much more like a motorcycle - and it was this combination that won me over. I'd ridden a Silver Wing and an MP3 500, but neither had the combo of secure handling for back road blasts and enough power to flow easily with L.A. freeway traffic. That, and the full spectrum of modern motorcycling conveniences, won me over. The availability of 95 liters of storage without the width of saddlebags, and the comfortable and flexible riding position (I can literally extend my legs to locked knees, or ride bolt upright, or anything in between) is a thing of beauty. Can't wait.