Look at the newer Hydro Down which is a Teflon treated down that only looses a little loft but is water resistant and will still provide some insulation when wet.

I like a modular system with a silk or fleece liner, down bag, and then either a synthetic bag or bivy cover. I also go full length on a Thermo-rest type self inflating pad. The synthetics have not lasted as long as my down bags by less than half. They are easy to clean and best for float trips and continual rain though. Go with any of the name brands and it is worth paying for the higher loft ratings with those over 600 fill having fewer feathers in the mix. The 800 fill power bags feel like sleeping on a cloud. The Cat's Meow is too restrictive for me, I get a bag listed for at least six inches taller than I am so the hood covers well with no restriction. A good base layer and a balclava or beanie will extend the range of the bag. With a roomy bag you can keep extra clothes by your feet and get dressed inside the bag.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli