I'll second what these guys have said. Merino doesn't dry as fast, but it is much more comfortable when wet. You don't get the same chill as with synthetics, which leads to a much wider comfort range for active use. It's more resistant to odor (though not odor proof) than even the newest silver-ion impregnated synthetics.
That said I was recently given a piece of
Mammut Alpine Underware to try out. It uses three different fabrics, two wool/synthetic blends and a straight synthetic, body mapped to where you need the properties of each the most. I haven't personally worn it enough yet to give an opinion, but I have a couple friends who have been testing them for a year and love them, so I'm optimistic.
Prolite Gear should have them in stock this week.
Coincidently the wool/synthetic blend isn't a new concept. That is what Patagonia's wool has been (75%-25%), I believe from the beginning.
