I think you have to ask what itch are you trying to scratch. I personally have no interest in a bike like that, but there are reasons that there are different styles of bikes.
At 500lbs my GS is about the upper limit of what weight I'd put up with, unless I went with an RT with a goal of doing a few K miles a month. If I'm on a bike I want to have fun, and wrestling 650lbs isn't my idea of fun. On saturday I rode one of these:
That was fun...