Originally Posted by
cmoulder
Quilt warmth ratings from one person to the next and to the next and... etc... are VERY subjective. Some people are warm at or below 'advertised' ratings and some cold or very cold sleepers require a 10, 20 or even 30 degree or more buffer. Manufacturers' ratings vary somewhat. A lot depends on the effectiveness your ground insulation... many times quilts and sleeping bags are blamed when the real problem is an air mat or CCF mat (or both) not getting the job done.
Does your 20°F quilt keep you warm at 20°F? Or colder? If you're completely comfortable at 20°F then you'll not likely notice much of a difference with a 30 degree quilt.
However, if you want the lightest, most 'stuffable' quilt you must pay attention to the shell material, which has far more impact on compressed size and weight than down does. For instance, a 7D quilt with 850FP down will compress smaller than a 20D quilt with 950FP down, and will weigh significantly less. Of course, the best of both would be 7D shell material with 950FP fill. I have a 30deg Enlightened Equipment Enigma with those very same specs (7D, 950FP — no overstuff) and it is one of the best things I've ever purchased. It weighs right at 400g and has been totally warm *for me* down to actual 25°F. But again, that's me — one data point. And besides EE there are not many cottage companies, and certainly no mass market manufacturers, using 7D material for quilts.