My neoair basic early model is crinkly but with my sleeping bag on top, it doesn't bother me. It might bother other people who are more sound sensitive but compared to other sounds in the tent, plus just being so tired after a days ride has meant it's not been an issue. It's possible the newer ones are quieter.
Just remember trying one in a store will be louder without a sleeping bag on it.
As for r factor, whatever mine is (probably very middling) it's been fine in the temps I've camped at, lowest maybe 5c?