West,
I have used silk for a long time and like some of the other guys have found it hard to find. Merino over silk has always worked for me however this year I purchased the KUIU 145 and 210 Merino underwear.
Actually purchased it late last year after I returned from a trip to Colorado where one of my good friends was using Kuiu gear including the underwear. My silk was about wore out and I still have a few pieces but will probably give it away.
I have never experienced anything that wicks moisture away and through into the mid layers like this stuff. Had 145 base and 210 over it this past week in Alberta with an 850 fill Super Down zip T under the Chugach wind breaker/rain gear jacket.
The down garment caught all the sweat and is actually the wrong choice for a mid layer when walking a lot. I did not get cold and the wind was blowing 30-40mph on the downwind side of the mountains. On the ridges it was hard to stand up with a pack on it was blowing so hard on Tuesday.
I know the stuff is expensive and I would never by it choosing to "bull it" and use what I was used to. I cannot say enough about there products. Used it in Mongolia in late September and the first of October in the Gobi and the Altai and again this week in south Alberta.
Zips down each leg so you can layer it on or off without taking your boots off. No more silk for me..

Dave