Perhaps wool clothing is even more important not only in the back country but even in everyday use due to the greater dangers for transport and the potential for suburban and city fires within the home, office and workplace.

There are some really high performance synthetic and wool garments available for the wilderness. Just choose what works for the conditions and your preference.

For example a Merino Wool Sweater such as a Harkila Clifford Cardigan with a Goretex Windstopper lining makes an excellent replacement for Windproof Polyester fleece. Keeping both wool and synthetics dry is important to keep insulation properties. This can be achieved with a Umbrella in rainy ambient wind conditions and a Goretex Shell in rainy windy conditions.

Even a Merino sweater such as the Columbia Sportsware Exploratory Sweater combined with a Cotton Ventile Windproof will work over quite a range of temperatures.

I do like Merino Wool as I find it tends to regulates body temperature over a wider range of weather conditions than synthetics. Wool can be very comfortable and warm just like cotton. To keep it dry is the trick to keep warm just as with the synthetics and down feathers.

When conditions are very dry such as 0F then even down feathers start to become very useful for insulation.

For cold weather I also like my Laksen Knitted Wool Hat with Goretex lining.

http://www.swillingtonshootingsupplies.co.uk/store/product/8229/Laksen-knitted-Ctx-hat/

A thin merino wool glove liner is nice to have as well even under a waterproofed synthetic glove.

There are some really nice comfortable and functional high technology wool clothing out there. Synthetics do tend to somewhat lighter in weight though but also a lot more stinky when worn for a time in the back woods.