"I too have looked at my long hair cat while thinking that her fur would make excellent down material. Has anyone tried? Does a wet cat smell like a wet dog? The hair is incredibly down like and not greasy at all."
Haven't done anything with cat hair, but did with Angora rabbit fur. I sprayed it with a fluorocarbon DWR treatment, mixed it with some 550 duck down, and then put it on top of a layer of 2.5 oz Apex. No baffles, i wanted to see how it would tend to stay or shift without baffles. Haven't test it out yet because it was heavier than i wanted it to be. The lady who sold me a "1 lb" of it, gave me more than that and i hadn't bothered to check the weight before hand.
Anyways, quality Angora rabbit fur is very warm stuff. It's both rather fine/thin fibers on average, many of which also are rather hollow.
That's a great combination for trapping air. But, i don't think it would hold up to compression as well as down would, and it might matt or felt some (which is why i sprayed it with the DWR, hoping it might make it more slippery and less prone to same).
Unfortunately, i could not find any CLO type tests on Angora Rabbit fur, since a lot of people saying general things like, "it's 7" or "8" times warmer than wool, which doesn't really mean a whole lot.
It would be more ideal for smaller insulated garments, like mitts, maybe vests, etc. things that don't have to be compressed too much to put in ones pack.