Th R1 is a solidly warm and versatile top. I recommended it for a cold weather base or for just hanging.
I own an old version in a XL that runs a more athletic (tight) fit. When replacing that one which is starting to get holes, I had to return an XL and get a large. The current large is at least as big if not bigger than the older XL. Be aware.
This review was written in the old system and had content requirements that are different than reviews written today.