I've had my North Face Cat's Meow (20 degree synthetic) sleeping bag for about 3 years now, and it's served me well through many nights. On the other hand, it weighs almost 3 pounds and is the size of a watermelon at its most compressed. I also must be a real cold sleeper, because I've been on the cold side in it even in 30-35 degree weather before.
Anyway, for bikepacking purposes, I'm interested in something more compressible, and lighter. I'm a little leery of down for the usual water-related reasons, but it seems like the way to go – I don't think I'm that careless that I'd end up with a wet sleeping bag anyway.
I have no idea how to pick a good sleeping bag; I got my first one solely on a friend's recommendation as I was getting into backpacking. I'm also a hammock sleeper and I know quilts are all the rage; are there any reasons not to use quilts on the ground? What other criteria do I need to look at to judge what I need? I'm looking for something in the 20-degree range again, for all-purpose use and long trips (I'm planning a cross-USA trip either this summer or sometime after) and being warm enough if it does get down to 20 is more important than having the absolute lightest option possible. In a hammock, I'll be sleeping with an underquilt once I get one (foam pad until then) and when on the ground, on a Thermarest NeoAir Xlite in a Big Agnes Fly Creek 1 tent.
Any recommendations to help me in searching would be great!

