Thanks again. Right as you posted, I was just about to copy and paste some great info I got after doing a search on this topic. Well, I can still paste it...it just further edifies what you just said, and makes sense to me.
"Heat tends to move upwards and pass through the inner layer just fine, by the time it passes though the second layer it tends to cool and turn into a vapor which starts to accumulate in the outer layer of the sleeping system. With down being the outer layer that would start to compromise/collapse the loft, synthetic insulation tends to handle this moisture build up lessening the chance of loft degradation."