Pros: fabric feel, warmth, sweat handling, price vs other wool brands
Cons: price versus synthetic options, zipper
I've seen ads touting Merino wool over synthetic fabric as a base layer, but didn't give them much credence until trying the Minus33 mid weight bottoms and 1/4 length zip top that I recently purchased. Wool costs more than synthetic and normally I went for what looked like a bargain. However, I had a chance to pick up some Minus33 base layer clothes at a price just a little higher than a good synthetic version and decided to give it a try for the ski season. I'm glad I did. I haven't had a chance to try them in a full winter onslaught yet, but I was able to use them exercising outside on a cold, windy day and they performed well and felt better than any synthetic version I used.
The Minus33 1/4 zip top and accompanying bottoms performed well the one chance I had to use them so far. I wore them to take a run when the temperature outside was tool cold to just where shorts and and a t-shirt. I wore the bottoms and the top with just my running shorts over the bottoms and felt comfortable temperature wise for the whole run. I never felt too hot, even though I often build up a lot of heat when I run and I never felt cold either. The 1/4 zip top and wool bottoms helped keep me in a comfortable range.
Once I finished my run, I got to be impressed by some other qualities of the wool. First, I sweat a lot when I run and this run was no exception. But, I didn't feel particularly sweaty during the run. When I got in and took the bottom and top off, I was able to see that the wool had absorbed a lot of sweat from me kept me comfortable despite the sweat. Next, the bottoms and tops dried fairly quickly and didn't smell at all, even the next day.
There are a couple of small negatives. The zipper felt like it could break with a lot of use since it is thin and small. Now this may be to make it more comfortable against your skin. This is the first 1/4 zip base layer top I've owned, so this may also be normal for this type of top. The other issue comes down to price. Wool is more expensive than synthetic and if you compare the price to that of a quality synthetic brand, it is going to cost more. However, if you price it against other premium wool base layer brands, the Minus33 clothes can be found for less, and are thus a good value compared to other wool brands.