JamesNoBrakes

I do a lot of cold-weather stuff and outdoors stuff. I find it to be fairly over-rated. There are some recent studies looking at heat loss and insulation that find the difference between synthetics and different types of wool to be marginal. I tend to wash my stuff pretty religiously (but you have to do it smartly, gentle cycles and hang-dry insulating/sports-wear type clothes), so the "smell" issue never comes up. More important to me is having the right layer weight/thickness and breathability. If it can't breathe enough, you'll be miserable. There's a tendency to always to too far to insulate and feel comfortable before exercise, which usually leads to lots of sweat and sticky clothing, with hard-shells and gore-tex trapping lots of heat and moisture.

One thing for sure, I'm not going to wear a pair of undies more than a day...merino or not.