The supplex was on sale when I was buying noseeum for a bivy, and I have down (not 800 fill, maybe 650) from an old coat and vest. I haven't made anything so complicated as a quilt/bag before, so I thought it might be nice to experiment without much money invested and make a little summer bag. Poor college students can't quite justify the lovely momentum, especially when I have a serviceable 3 season bag already.