Used these for Ice Fishing over the weekend.  It was -2F when we got there.  It made it to 14F by the time we left.  I was very comfortable while just sitting and even worked up a sweat while dragging the sled out onto the ice.  I only wore sweats underneath and don't see a need for anything more.  They did just what I wanted them to and with the Cordura shell, I bet they are the only thing of it's kind I will ever need.

Fit:  I did get to try some on at my local Carhartt outlet so I had a good idea what size to get.  I wear a 34/34 in the dungarees.  So I stuck with the 34 length. They pile up on my boots a bit but I am good with that as I think the 32's would have come up too short.  I went with a 36 on the waist because my gut is a bit bigger than my waist.  This still allows room for more layers on top.  Though I may have been wearing one too many layers there and even took my parka off for a while.  I think these actually cover enough of the torso that you may not need as many layers on top.