A couple comments
I don't disagree with the editorial disclaimers, but since I'm just doing some relative measurements I believe my conclusions, although there is some uncertainty.
One thing I don't like is that I measured in my office and the temperature inside the insulation was not typical of skin temperature (90 F). I may repeat this outside under the night sky with 90 F "skin" temperature and outside temperatures around freezing. This especially affects the IR heat loss - my data is just a hint of what might be happening.
In my opinion, it's too difficult to include humidity, but I would like to measure insulation that's wet - have to have skin temperature that's 90 F and outside btemperature about freezing.
You like your down better because, like Roger said, the clo/oz/yd2 is smaller - less weight for the same warmth.
And as far as having the fewest number of layers, I know this goes against the conventional wisdom, but it's just that extra layers have extra facing fabric which weighs a few ounces but contributes little to warmth. Yeah, more layers is more flexible. I have used just three layers - base, insulation, and rain jacket - for years in the Pacific Northwest in the winter where it rains a lot and down to 20 F. If you add an extra layer, it only adds a few ounces, so that can work good too. I give a few numbers so we can talk about this quantitatively.
One thing that really bothers me is that I disagree with Roger and Richard Nisely about overstuffing down, because they are more expert on this subject than I am. They say adding down increases warmth even if it doesn't increase loft. I have repeated this measurement multiple times and come to approximately the same result. Someone recently posted the link http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=12505&startat=20. On page 2, there's a plot of "The effect of down density in a fixed baffle size on the insulation value of sleeping bags". On the left side, there's a clo of 4.4 for 16 ounces of down = 0.275 clo/oz. On the right - 5.73 clo for 28 ounces = 0.2075 clo/oz. So, for a 75% overfill, the clo/oz decreased by about 25%. This is pretty close to my data - for a 82% overfill, the clo/oz decreases by the same amount, 25%.
What difference does this make? If I'm making a down garment, overstuffing by a little, like 10%, will make sure all the baffles are completely filled, but if I overstuff by a large amount, like 100%, then I've lost the advantage of down over synthetic, but I think the down will be much worse if it gets wet.