I really gave these boots a shot, wearing them on two trips to Alaska. Unfortunately, I have to downgrade my initial rating:

I first wore them on a trip to Anchorage and Fairbanks in March 2011. While they were comfortable and seemed solid (and I rated them well for that), my feet were kept warm mainly due to my heated sock liners and not because of the boots. When the liners were turned off, I could feel the cold radiating up through the boot soles. I thought this might be normal, however someone here (from Alaska) commented that I should not feel the cold coming up through the soles (see comment section).

Before my second trip to Anchorage and Fairbanks in February 2012 I bought a pair of Sorrel insoles which were much thicker and more solid, and inserted them into my Northside boots. While my feet felt warmer initially, I discovered on my arrival in Fairbanks that my boots had developed a leak; cold water seeped in when walking through a parking lot of packed snow (no snow got in over the boot top).

Between the two trips I have worn these boots just under a month, and just for walking around town. While I may have received the odd defective pair, I have decided to go with another brand on my third trip to Anchorage and Fairbanks in January, 2013.