I am not a sleeping bag guru. This is not a challenge, but a genuine question smile.

I looked up the JRB and WM offerings and it seems that for a similar temperature rating they are of similar weights. For example:

JRB High Sierra Sniveller quilt
Temperature Rating: 5°-10°
Weight: 29 ounces

WM Versalite sleeping bag
10° F
1 lb 14 oz (30oz)

I would think that the ability to close it up could make a bag it warmer than a quilt should the need arise. When the temps are mild the bag could be used like a quilt. What am I missing?