Used the 9cm Deluxe Mat with pump on the Arctic 2010 exped....
Like most folks here I understand clearly that heat is wicked away by lying on the ground.....it is not until you have slept on one of these that you appreciate the extent of the heat loss..
To put it into perspective....
Army Arctic sleeping bag, in an SF Bivvi bag.....stripped down to just my trolleys...even the socks came off :yikes:
Because of the insulation provided by the mat, I had to unzip the sleeping bag to half way down the bag, as I was overheating and generating too much moisture. (Not good in a seriously freezing environment)
It averaged minus 18 overnight folks, measured inside the tent, which had a box log burner going like the clappers and five other bodies in it.....
Some other folks did not fare so well, even with a 'combination' of foam mats and reindeer skins on branches / boughs as ground cover...it was uber cold....
Best investment I made for the entire trip. Comfy too.....
Hope this helps
Tom