Just this last winter, I bought a Merino sweater. It was thin, but kept me much warmer than I expected. Without a doubt, this material outperforms my polyester athletic sweater on a pound-per-pound basis (although my poly sweater is big, bulky, and still warmer). All winter I washed the merino sweater as instructed: cold water only, hang up to dry. By the end of the season, this thing looked like a nice fit for my ten-year-old. My mom, bless her heart, said she wouldn't mind cutting up the sweater; she could make me a pair of socks and gloves out of the material. If it doesn't shrink even more.
While my polyester athletic sweater doesn't quite perform as well as merino wool, at least I can still wear it. And it does a fine job of keeping me warm in the extreme cold.
Maybe I'll take that merino sweater and just wash/dry it over and over until it stops shrinking -- it has to eventually, right? Then my youngest daughter can use it on one of her barbie dolls.