As usual OM is spot on. I can only add three things.

1. A ground quilt needs to be wider than a hammock quilt.

2. A hood or hat is very important for a quilt.

http://katabaticgear.com/shop/category/hoods/

3. The colder is gets the wider the quilt needs to be to limit drafts. For winter camping I use the Katabatic Sawatch under a Jacks'R'Better large quilt.

http://katabaticgear.com/shop/sawatch-sleeping-bag/

http://www.jacksrbetter.com/Large%20Family.htm


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"In theory, theory and practice are the same. In practice, they are not."
Yogi Berra