I love the rubber, however, on the premount, the rims are hard and brittle.
Grip and wear are very good in the scorching heat where track temp easily reaches 60C.
I could get at least 15 good 5 min runs using 10.5T on an abbrasive technical track where a fast lap time is in the range of 13s.
The rubber is more firm comparing with Sorex 36 and is comparable with Sorex 40.
I would use them as training tires, mounting the tires on other than the premount rims.
Sorex 40 is a bit more loose/faster.