For what it's worth....

I toss all my smartwool socks in with my regular wash (usually on cold) and they ALL go straight into the dryer on regular temps. Most come out *looking* very small, but as soon as they go on my feet, they are back to their normal size again.

I also machine wash AND dry all my smartwool, ibex, sugoi and icebreaker base layers. I would say they initially shrunk a few percent, but that's it. I've had some of these items for YEARS and the washer/dryer routine doesn't seem to have hurt their performance one bit.

YMMV, but my experience has been good overall. In the winter time, they all come out of the dryer with a bit of static cling, but they're base layers so I don't especially care. If I wanted less static, I would probably hang dry them.

Susan