Re: North NM in December
If you are on the move, stalking and hiking, I think you will be fine with 400 grams of insulation as long as they are waterproof. I just got back a couple of weeks ago from a 2nd season rifle hunt in CO. We hunted in 12+ inches of snow with lows in the teens during the morning hours and my Kenetreks did fine. My feet did get cold in the early hours but warmed up nicely. For me, sweating in my boots is worse than being just a bit cold.
Start young, hunt hard, and enjoy God's bounty!