Icebreaker make clothing items for all layers; underwear to outerwear.
Polar-fleece is not early as good; it loses it's insulation properties when it gets wet, so it is cold when wet, whereas wool is warm wen wet. Polarfleece catches fire and burns making it dangerous in some situations, wool doesn't burn, and polarfleece stinks when dirty whereas wool doesn't smell nearly as much (important for extended outdoor work).
Both wool and polyester fleece have their benefits and are proven in cold and cold/wet conditions.
You are incorrect regarding the insulative qualities of polar fleece. It insulates relatively well when damp. This is why it is specified by so many organizations, including the U.S. Antarctic Program, virtually all 1st world militaries, and many national canoing associations. Being hydophobic, it never gets as wet as wool since the water runs off fleece by gravity. It also dries from body heat alone if the source(s) of moisture go away.
Within limits, wool actually does better than merely insulate. At a penalty of gaining weight, wool is exothermic, actually generating heat while absorbing up to 30% water by weight. Past that point, it ceases to generate heat and loses its ability to insulate. It is far more difficult to dry "in the field."
Wool is greatly superior to polyester when flame, sparks, or exteme heat are a risk. Most nylons also do not deal well with flame, sparks, or extreme heat. Because some special nylons are designed to deal with heat, they are the material of choice when exposure to flame is a serious risk. (Ever try to fuse the ends of a Kevlar rope?

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Since polyester fleece does not absorb sweat, it may smell worse. It is also machine washable and field washable, making it more likely to get cleaned "in the field" if necessary. It is also far more abrasion resistant, hypoallergenic, softer (Morino wool, alpaca, and lama products not considered), insect proof, far stronger, far lighter, less wind-resistant, and cheaper (except for those cool "boiled" wool garments the Germans, Swedes, and others have put on the surplus market. :thumbup: )
So, like most folks, I enjoy my wool stuff and my fleece (and pile) stuff.