Oh yeah, Lonnie and I have some for socks, it is so YUMMY (the Schaeffer Anne).
As for the merino, I think it depends on the yarn, and the wearer...for example, I knit a pair of socks for Lonnie using some of KnitPicks older (no longer made) hand painted sock yarn which was 100% merino and it was handwash...he wore big holes into the bottom of the back of the foot after several wearings and washings.
I usually would have carried along Wooly Nylon
(a stretchy nylon that is used alot with serger sewing machines) but I forgot, I don't know how much it would have helped, though because he really puts a lot of wear and tear on his socks.
And there are 2 schools when it comes to carrying along nylon of any kind...some say it's great and really helps to reinforce the sock and then there are those that say the nylon cuts into the yarn...so
what do you do?! I don't know. Even though I still have several hanks of 100% merino handwash sock yarn (I will probably knit it for me) I am switching to using sock yarn that is made to be washed.
And, I have also heard that, as you said, Sean, that spinning mohair into your yarn will strengthen it, too....I wasn't of much help, huh?!