Well, my understanding of wool fabrics versus synthetics is this that they each fall under the same category as insulating fabrics, but they each share their own unique traits.
Wool itself retains a little more of it's loft, and consequently it's warmth factor when wet. Synthetic insulations such as Helly Hansen Fibre Pile and HyperLoft used in sleeping bags tend to matt down a little when damp. (But not at all like cotton)
On the other hand, wool takes much longer to dry out, and synthetics regains their original dry factor much quicker, which makes them lighter weight.
New age wool, such as Merino is from a "super sheep" and the individual fibres are of a much longer staple, which makes them much softer than their predecessors.
Now, in terms of wicking and moisture transfer it is a completely different story. Wicking itself refers to a fabric's ability to "suck" vapour off of your skin, keeping you dry. Wool is able to do this because of the structures of the actual fibre, it is able to absorb up to 30% of it's weight in water and still feel dry to the touch.
MVT (moisture vapour transfer) is inherent to synthetics. Because they are essentially plastic, they do not actually pick up water vapour. Instead, heat from a hard working body literally drives vapour away, through the fabric, and disperse it to the outside air. This is why synthetic fabrics feel clammy when damp, because they actually move moisture away from your body at a much higher rate than wool.
I personally do not think that any one fabric is perfect for all situations, even though most of the big gear manufacturers say theirs is better. Companies like Gore-Tex even go so far as to design biased laboratory tests against their competitors to gain a larger share of the market.
One must use common sense as to what they will wear in what situation. I like wool in cold weather, in fact I'm wearing an army "wooly pully" sweater right now, because we had a bit of snow last night.
Whew...long post!
Just my $0.02 cents.
Adam
