Just got these in the mail yesterday. Under garment clothing (long underwear) has always been problematic for me (weird sagging in the crotch).  Perhaps with the fabric combo (opposed to the waffle textured) of these pants, they are better designed to fit. I love them and compare them to my yoga pants only softer.  We are going on a backpacking trip next weekend and will be wearing these.  I'll update my review at that time.  I'm interested in the pant's ability to keep me warm, wick away sweat, and durable enough for mountaineering.  I also liked that Duofold brand is a spur off of Champion.

UPDATE - 9/17/12. The 3 day bakpacking trip was a success.  I was shocked how comfortable these felt on my skin, they were flexible, and most important - WARM!  These are a cold weather staple for sure!