I have the silk and thermo-pants. The wool socks are sometimes accompanied by a disposable heat pad. The T shirt keeps the jacket clean and the jacket has a dependable hood for my head. There is a lot of wicking and breathing going on under a quilt, when it is very cold outside and this also works well before bed, fireside. Wrapped up in things that contain the heat don't work as well, the moister gets to me turning cold from the outside air. I stay naked on the trail and minimize clothing as much as possible, sometimes disrobing to be under the quilt, in the net tent. That net tent works with the same principle. It doesn't trap the moister and the air is fresh.
I had to experiment, to get my head around that.
Jbee