Rule number one: "merino keeps you warm even when wet".
Rule number two: "never get your layers wet in cold weather".
Rule number three: "you'll sweat when active in a merino base".
I've never been able to square this, so I wear capilene as a base and synthetics over that in winter, until heavier layers. But I understand that lots of people love merino, it works for them!
Still, I'd wear the lighter merino layer and not sweat in the first place. Otherwise probably the merino over the R1.