I own an '09 MP3-500. It will run w/the big boys & still get 50 mpg (on hi-test). As you said, heavy. A lot of fun, but you have to stay focused when riding. Steering is quick, & smaller wheels (than a regular MC) mean you don't have the stability of two big gyroscopes spinning under you. Machine is complex & has it's own peculiarities to deal with. There is a forum dedicated to the MP-3 as part of "Modern Vespa".
ronkom