If you do a search on here you'll find quite a few threads regarding quilts, pros/cons, etc. I think properly set up they are every bit as warm as a bag, with the exception of your head (quilts don't wrap around your head). The biggest thing with quilts is eliminating drafts. Most quilts have some way of strapping it to the pad to keep the sides down on the pad and keep the quilt wrapped around you. I sleep in a bivy and that keeps everything contained so I don't bother with the straps anymore. The biggest pro IMO is the elimination of all that material and zipper (weight) that you sleep on in a sleeping bag. When sleeping in a traditional sleeping bag, all of the bag that is under you is being compressed and your getting little to nothing in the way of insulating properties from that. The insulation is almost entirely from your pad, so, by using a quilt you can help cut the overall wt. of your sleep system. Another advantage, I would guess, is price. When compairing apples to apples, quilts are generally cheaper than bags. You can buy an American made (and very well made) 0 degree down quilt for around $300 or less. You won't find a similiar bag (0 degree, American made, down) anywhere near that price.
