Well after just getting by last winter I finally got smart and tried out a merino wool shirt to use as a baselayer. So much better than the UnderArmour type stuff I had been using. It breathes better and certainly does stay warm while wet.
Then I added in a long sleeve merino wool jersey and it is even better. Able to wear these two lightweight layers under my foxwear jacket in temps down to the long 20s with complete comfort.
I will also add that I am quite sensitive to traditional wool and can't stand to wear the stuff. But these merino wool products are soft and totally itch free. And they have yet to develop any kind of odor to them and can go for days without washing. They truly do work as advertised.
Now to save up for a wool outerlayer and I will be completely hooked up for the winter. Like many here I bike year round and know I will see temps well below zero several times this year. Quite a comfort to find products that really do hold your body heat even when wet.