For a point of reference for you, I own and use a JRB Hudson River quilt (2.5in loft, 20oz), I use it in temps in the high teens. For a 6' person the long at 22oz would be a similar comparison. The Old Rag Mt quilt at 27oz (3.5in of loft) is good for single digit temps.

http://www.jacksrbetter.com/Rectangular%20Quilts.htm
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