I have used this jacket extensively in the Adirondack park, ice climbing and snow shoeing. It is extremely light and warm. I wore it as my outer layer snow shoeing in single digit temperatures and it was more than warm enough by itself. I wore it as a mid layer ice climbing this February under an EB hyalite soft shell when the temperatures were below zero. It is a heater under a shell. Was never cold even when the day was -10 and the high was 0. As for sizing XL fits me well 6'2" 200 pounds. ( I initially ordered a large but it was too tight through the shoulders and arms.) The long arms come into play when climbing preventing the sleeves from riding up your forearms. And being super light and compressible did not weigh me down. This jacket goes with me on all my adventures and expeditions.