Mitchell: Nisley gives the Iclo of an inch of 800 FP down at 6.562: "800+ down fill is 6.562 clo per inch" in thread 9378. By comparison, an inch of cotton reportedly gives a CLO of 4. Perhaps the loft measurement is the culprit as you say. I've given my jacket multiple loft measurements, resting a light ruler across the top of several baffles, and using another ruler to measure the distance from tabletop to bottom of horizontal ruler. I pretty consistently come up with 7/8 for a double layer (.44 for a single layer) over multiple attempts to measure. So your parka still appears to be significantly loftier than my jacket.
Rick you may be right, but if you are, you contradict several posts to the contrary, which state that Uniqlo use either Japanese or Euro scale (different posts reference different scales), one or both of which are reported to be lower than the US scale. I've also read several mentions here on BPL that the Uniqlo down doesn't have the look and loft of American 640. But...I don't have first hand knowledge here, just reporting what I've read. I've never gotten the impression that the +100 is definitive. But then, we're far into the Nerd Ether here.
I haven't a clue to where you'd go to confirm or disconfirm that Am, Euro and Jap ratings for down FP are different or the same. I've just read plenty of posts declaring they're different, and that the Am is "inflated." Perhaps someone can furnish a reference.