I still have a pair of the FL Allegheny merino base bottoms that don't have a single hole in them. I've had them at least 5 years and I wear them every elk season for at least a few days at a time before changing them out. Last year my brand new Minus 33 merino bottoms developed holes in just a few days of wear. Every season I still wear a lightweight merino top from Cabela's that I bought in 2007. The ends of the sleeves are frayed, but overall it's still wearable. The same bottoms on the other hand, have officially been retired. They lasted awhile, but now seem to have more holes than material. But I'm still a big fan of 100% merino over the blends, even if I have to replace them more often.
I actually tried to burn some of the frayed ends on my Cabela's top, and they certainly don't burn or melt like synthetics do. And they were made in China.