I ordered one of these hooded wool shirts to use as a base layer for cold-weather riding, but I wasn't sure about the sizing. First off, I have a 43" chest and I ordered the Large, which has a 40" chest according to Cutter's unique way of measuring. Spot on for me: form-fitting but not super tight.
On rides when it's in the mid-30s I've worn this under a long-sleeve jersey and a midweight jacket. I start out with the hood up over some earwarmers, and then midway through I might peel back the hood. If it's in the upper-40's you might get by with this and an insulated long-sleeve jersey. It's not super, super warm, but it allows you to layer nicely. And no scratchiness against the skin. I love it and just ordered two more at Bonktown prices.