The idea of a quilt is that the bottom part of a sleeping bag will be compressed by you lying on it anyway. This will minimize the insulation by decreasing the filling’s loft. The quilt saves weight by being open at the bottom. This also makes it much more versatile than a normal sleeping bag as you can also use it as a blanket. Some quilts also have a small opening for your head so you can use them as a poncho in camp, saving you the need to take an extra puffy jacket with you. Once you go quilt, you never look back.
A high-quality lightweight bag of either style will be built with 800-950 fill down. Some are constructed using water-resistant fabrics and there are even companies using water repellent down.
One critical piece to include with your sleeping bag is a stuff sack to store it in. You always want to ensure that your sleeping bag or quilt is going to be dry and stay that way. If it does get wet, take an extended break to dry it out. On many trips, I like to pull out my sleeping bag and let it air out over a lunch break to dry any moisture from perspiration that may have built up throughout the night. This will ensure you are getting the most out of the R-value of your sleeping bag – something that becomes important the colder the temperatures dip. Wet down becomes useless, but is definitely the best choice when it comes to reducing your weight.