I have used 3 bags extensively for long distance hiking (along with several others). I'm also not sure that I agree with this big concern about down getting wet. I got pretty wet during a bizarre Memorial Weekend snowstorm (12+ inches) in the Angeles Crest Forest (or whatever it's called) in '08 while camping under a poncho tarp (I choose a larger tarp now) and I didn't have any problems the next night.

The Jacks are Better Sniveller quilt - it's a little too narrow for a side sleeper unless I bring a bug bivy which keeps the sides close to the ground. This is pretty bulky (for down) though but good to at least 25F with a tarp.

Montbell Super Sleeper #3 (I think) - This weighs the same (or more) as the JRB quilt but there is almost a 10F temp difference in warmth and I haven't used it for awhile due to the JRB being better. Overall this is a really nice bag though.

Mammut lightweight synthetic that weighs about 1 lb (18? oz perhaps) and is rated somewhere in the mid 40's F.

At some point I should get the JRB Sierra Stealth but it would only save a few oz's and there are more important things to spend money on.

edit - forgot to mention that the JRB quilts have a head hole (velcro) and can be worn as a poncho. Not easy to move around in but really nice in camp on cold days when your only options are to be in your sleeping bag or shivering.