I NEVER leave home without it. As a base layer this stuff is awesome!! Especially if you work up a sweat walking in. It wicks away so you don't get cold and clammy.
I know in your initial post you said you don't want to do layers but really its the best way to keep warm. Here is how I dress for 40 degree morning. (Upper body) First a layer of cold gear, then a heavy duty fleece shirt, fleece vest (the vest is the key for keeping your core warm) then a mid weight jacket. Mine is from Dick's, its their Field and stream brand, cost me $50. I made sure it had a good shell for wind breaking. And make sure it has a hood. (Lower body) Cold gear, fleece sweat pants, then heavy weight insulated pants. Last ly and my most effective weapon against the cold, a good tight facemask. Sure you can put on the war paint like the nuts on Buck Commander but a facemask gives me at least an extra hour in the stand. If the mask interferes with your anchor, watch what Lee Lakosky does with his.