I've been through three sets of them on the M5 in years past, have a set now for the M3. I've used them so I can drive to events, like at the PerfCenter -- as long as you're careful if it's wet, and stop if it is raining moderately or more. For the most part, they are very resistant to heat cycling out as they pretty much "stick 'till they cord".
The NT-01 is an low level R-comp tire and spans the gap between serious R-comps (Hoosiers, BFG R1, etc) and max street tires well in that it has audible feedback on most surfaces, and if you are over the peak of the lateral force/slip angle plot, it doesn't just drop right off super quick, so it is more reminiscent of a street tire in that regard. They are also "tough enough" to drive on the street unlike a Hoosier which you'd *never* want to drive on the street.
I've also used the BFG R1 and Hoosier A6. Both of those are a significant step above the NT-01. I prefer the R1, especially the R1-S, as it has fantastic grip, wears well, and communicates well through the wheel/seat. The A6 is a pure purpose autox tire, but in sizes that fit the M5 (275/35-18), is not well-suited. Grip is great, turn-in feels vague, but even with -2.4 front camber, the infamous Hoosier A6 "edge of death" will appear on the outside edges. The BFG R1 will easily last 2-3 times as long as the A6 before cording.