price isn't an issue for me, but i still don't want to pay a premium just for rarity's sake. i've been looking into icelandic down because they specialize specifically in authentic eiderdown, particularly the traditional process of hand-harvesting it from wild duck nests after the birds naturally leave. the idea of an ethically collected, extremely lightweight, and warm duvet really appeals to me.
for people who have actually slept under genuine eiderdown, what performance factors make it worth the investment?