Over the years I've collected dozens of sleeping bags, and survived them all! My first snow-camping kit was two ultra-cheap nylon sleeping bags, one inside the other. As warm as my subsequent Blacks Karakorum down bag (then the ultimate bit of kit for bike rallies), but not as comfortable. Thats also when I found out that - despite a decent waterproof tent (Vango Force 10 Mk 5), sleeping bags could still get wet for a whole variety of reasons, and when they do, down bags are a complete bust. Which was when I got my first fibre-pile bags (Survival Aids) - they made an inner/outer combination that you could mix and match depending on the temperature, and had nifty gadgets like zips so you could stick your arms out whilst the rest of your body was still in the bag. The key feature however was that they retained heat even when wet, much better than an equivalent "artificial down" bag. I still have - and use - one of these some 30 years after buying it (in fact it stays in the car for those Just-in-case situations). I believe Buffalo still make something similar. Really easy to wash too.