I've had a few stories from my Dad (he used to ride them in London when he was 15 up until the age of about 26, and he also did track racing on Brands Hatch and Silverstone and some of the other big tracks down there), but no real experience myself. I wouldn't mind learning about them, though. He's looking at getting another bike because the fuel prices have shot up so much. Some of the ones he's been telling me about are mental! 0-62mph in 2.5s, top speeds of over 250, a standing quarter in about 4 seconds, reaching speeds of over 150 in the distance.