From Pan's article "Nesting tricks from an old coot" there is this:

Minor down compression (up to 50%) does not reduce warmth in down insulated gear according to studies conducted by the Department of Defense Cold Weather Laboratory in Natick, Massachusetts.
So, how about that? I find that pretty surprising, but I am very happy to hear it. So, if I compress it to 2" under my back/butt from the original appx. 4" loft( or 2.5 down to 1.25 or whatever), it might be nearly as warm anyway?

Another way of looking at it: If when attempting to adjust my PeaPod or a non-snug type UQ, I sometimes have to choose between maximum loft and the pods/UQ's contact with my back. Sometimes if I adjust the pod until it just barely contacts my back, I will then notice that loft seems to have decreased quite a bit. The amount varies with which hammock I use, sag angles and other variables. But maybe as long as I "only" lose less than 50% of the loft, I will be better off accepting this loss- which might have minimal effect- and maintaining a "no gap" adjustment?

If this is true, is it maybe related to the benefits of increasing down density with overfill, as has been mentioned here recently? IOW, down that is compressed has lost some loft but gained some density, it seems to me. The same amount of down in a smaller space, rather than more down added to the original space when the max loft is already somewhat limited by baffles.

Opinions? Thoughts, anyone?