maybe not as durable as a Mammut Genesis.
I've just bought a Simmond 8.9mm 80m single for £109.99 (Decathlon; free delivery):
Re diameters I believe that there is no standard of what tension, temperature, and several other variables rope diameters are measured at. Thus manufacturers will put a number on it they think will sell. Vaguely remember this from a company training day when I worked for outdoor shops. Grams per metre is a much better thing to look at. Second all opinions about simond ropes, used the 9.5mm loads, great for everything.