There's a really good post
over on the OUTLIER site about why they use merino wool: "Here's how it works: Merino fibers have a complex structure with a hydrophobic exterior (water repelling) and a hydrophilic interior (water holding). This makes the fabric dry to the touch yet wicking moisture away from the body at the same time. Combined with your body's ability to create heat, the fabric dries much faster creating a cycle of moisture evaporation. Not only that but it's also odorless and stays that way by being naturally anti-microbial. This means odor doesn't bond to the material because bacteria can't find a solid environment to grow on."
Not that I'm overly surprised, but
OUTLIER has nailed brand blogging (their style wouldn't work for everyone, but it's perfect for their site/audience).