The $8K, 420 pound, 90 HP Hornet looks to be a serious street flogger. Likely the thinness of the seat is secondary to the importance of that tailpiece keeping you from sliding right off the back when the old right wrist wrings the throttle WFO!
The 120+ MPH top end is way more than I'm interested in. The Interceptor's 45 ponies will easily do the trick for about $2K less. The GB750 does look a treat though...