I got my first set of merino wool long underwear last year before deer season. I got the 250 gram set. They are very warm and comfortable. I stayed warm in much colder weather than I expected them to keep me warm. They don't make me sweat when I'm walking in and out from my stands. I recently bought a pair of 400 grams. My plan for them is to wear both pairs at the same time to try to eliminate my insulated bibs until it gets down below 25 degrees. What experiences do others have with merino wool?