Well, what is your life worth?

With respect to temperatures, the temps I achieved were with a single use. Failure of the rope due to heat would be accelerated when under load and the results could be very ugly.

Another point. Decent, purpose made climbing rope is versatile. You can do more than rappel on it. Sometimes you have to go up, or traverse sideways, or help a less practiced or proficient partner over a rough spot. A good rope can work well in all these situations, given that it is properly employed. This is yet another situation where knowledge is more important than the gear.