I have driven this tire on two C63 AMG Black Series Coupes. The first was on the Nordschleife during an AMG Driving Academy event. With this tire, the C63BS could quickly catch the SLS AMG in the twisty bits. I was quite stunned by this, as my cornering speeds were so high that I had to brake aggressively to keep from rear-ending the SLS.
I followed this experience with several track days driving my own C63 Black Series, which came with this tire. Though it is soft and wears quickly, it is actually quite comfortable and not very loud at all. I have two sets of wheels/tires; one for street and another for track. Other than the price and how quickly they wear, I can't find a single fault with this tire. It is designed for the track, and is only DOT-certified so that you can drive your car to the track, instead of trailering it there. The SportMaxx is the best tire of it's kind, in my experience. I have tried the Pirelli Corsa and the Michelin Pilot Super Sport, in an attempt to find something better. Though the Corsa is good, it's no match for the SportMaxx. The Michelin PSS is not even close, IMHO -- the SportMaxx blows it away when the going gets fast.
This is NOT the tire for you if you want something you can keep on your car all the time. This is NOT the tire to take on the road -- or track, for that matter -- when it's chilly and wet. It needs temperature to operate well. Once it gets up to temp, it is the best tire of its kind that I've ever tried. Highly recommended!