I'm not quite sure what I think. It looks like something out of a commic book. I think the scariest thing is that there doesn't appear to be any kind of support for the rider; like you could just slip off or something.
As for the V4, the Ducati Desmosedici uses one based on their MotoGP liter bike. It is psycho. For me, money no object (about $70g), this is about the most beautiful street bike in the world: