In reply to ire: OK devils advocate here...
What rucsac were you wearing? What caused the pilling? Merino fibres are very soft and it is possible that if you were wearing it as a single layer and the rucsac rubbed against it this would cause the pilling, and in that circumstance, it would be under the "wear and tear/use and abuse". i my self have put a hole in a merino t shirt in one day. Pilling is a sign of abraison so something caused it, and arguably not the fault of the product
Ask yourself what caused the pilling, and is merino suitable against that product
remeber climbing gear comes with a caveat that states "may last as little as one use" or better put "shit happens"
i dont wear merino as a single layer as it gets damaged too easily, good thermal base layer though for when its proper cold