To paraphrase, there are bold rappellers, and there are old rappellers, but there are no old, bold rappellers.

It isn't clear what the potential advantage of using para cord might be. Right at my desk is a stuff sack containing 30 meters (roughly 100 feet)of 8mm kernmantle which I purchased to use on a favorite climb of mine. With a few slings and odds and ends, it is about the size of a loaf of bread and weighs maybe two pounds max. It can be easily carried anywhere and could be readily stashed in a desk or locker. With care, it will rappel nicely. So why mess with anything incomparably more dangerous?