I had them in the early nineties. The first pair I bought were great and lasted over a year with no punctures even though I was training and racing on the only bike I had. When I finaly got a puncture it was ahuge split and could not be repaired. I had liked them so I bought another one which ripped near the valve after about month and could not be repaired. I then bought yet another one which split again and could not be fixed. At £8 a pop trade I gave up at this point and went back to normal tubes at £1.
I thought about it at the time... and I wonder if they were perishing in the shop as the first set I bought were when they came out, and the last ones were from the same stock (I worked in the shop).