I own a lot of North Face and Arcteryx clothes but decided to give Icebreaker a try after reading raving reviews about natural materials. I have to say that my experience was disappointing. The merino wool is not itchy but is still too scratchy and uncomfortable to wear on bare skin. So I have to wear it with a base layer. Plus, this top is not warm, especially when its wet from the sweat. Its a good top to wear at home by the fireplace. For active sports or aerobic activities, Im sticking with North Face and Arc'teryx, they performed well on Mt. Kilimanjaro, Mt. Rainier, Mt. Hood...