My old Duofold lasted 20 years - seriously, 20 years - before the armpits started to tear out. It was the old style thermal underwear waffle-weave (not sure if that's actually what it's called), so I was disappointed when I first saw the smooth, almost jersey t-shirt feel of this new shirt.
However, I was very happy once I put it on to feel how comfortable it is. And warm. I will probably have to order a few more to have in rotation so I don't have to wait for this one to go through the wash.