The weight of the new BMW scooters are around the same as the Burgman 650. None of the big maxi scooters out there are exactly light. Due to a low center of gravity and smaller wheels, they most likely will feel lighter and more nimble than you would expect from their weights. I am really not interested in getting a big scooter myself, partly due to their weights, however, heavy really depends on your perspective. Yes these scooters are heavy compared to your GS, or a smaller scooter, however, I consider a Burgman 650 to be the scooter version of a Gold Wing. It's about 300 LBS lighter than a Gold Wing.
I ride, Therefore I Am.