I'll second Red Apple on the post for KLIM boot best I've ever had very very warm. A stiffer boot then my Sorel's but I don't mind that on the sled.
I use the adrenaline series but there is an Artic that's even warmer
http://www.klim.com/Arctic-GTX-Boot-3093-000.html#56558
Lets hope for lots of snow for some good riding.