Looking for warmer mid-layer sweater to wear under an insulated jacket. I wear a Nils sweater under my insulated jacket and on colder days, I add an insulated vest. I'd like to find a sweater that's warmer than Nils (rayon/nylon)...I've avoided going the nano puff jacket route because I love the look and feel of a sweater. Online, I've looked at Dale of Norway, Neve Designs, Newland, Ski Delaine, Erin Snow, you name it. What have you found to be functional rather just pretty?