I'm going on a late season elk hunt in Montana. Wondering if anyone can compare the warmth of a pair of puffy pants (Sitka Kelvin or First Lite puffy pants) versus the First Lite North Branch pants. On past hunts I have worn Sitka mountain pants to hike in and then pulled the North Branch pants on over the top to sit and glass. Trying to decide if the weight and space savings are worth the price of a pair of puffy pants and whether I will gain any warmth over the North Branch pants. TIA guys.