I made some updates to my note about vapor barriers. I will take some time to track down refereed articles... but from what I have found so far it really does look like maintaining a warm, high humidity micro environment around the skin does lower insensible sweat (aka transepidermal water loss).

Cool Mark, I have had good success with sleeping bag VBL's when
temps are subzero, particularly on trips of several days.

I also use vbl socks in my ski boots and a double vbl
(liner sock, neoprene booty, wool sock, bread sack) in
breathable hiking boots in snowy conditions. The bread sack
goes over both the sock AND the insole and is held in place
at the top of the instep with a bit of duct tape. This keep
not only the wool sock dry from sweat or outside water, but
the insulating insole too. It also prevents my toes from blasting
through the bread sack. I had a pair of bread sacks last for
5 days this way.

Mind if I post a link on my web site to this page?

Dave from Oware

Dave... feel free to make a link to that page.

Never thought about putting the outer bag around the insole. I will have to try that cause it sounds like it would result in less wear and tear. I can see how you would get 5 days cause you have smooth sock slighting in and out.