I've read up and found that common consensus is that the yarn softens nicely when washed, and that it doesn't felt all that easily in a cold wash, so machine washing is possible. To combat the possible flimsy quality of the single ply I've held reinforcing thread with the yarn while knitting the heel, and I'm probably going to do it at the toe also. If it's too chunky for the toe when I try it on I'll just rip back a bit and do it again with out. I don't find it all that stiff and difficult to work with, and since I'm making these for me, I'm sure they'll be fine.
I'm finally knitting Grumperina's Jaywalker pattern that I first saw a year ago. For some reason I've looked at this pattern over and over and decided that it was just too difficult to figure out, and proceeded to knit a plain stockinette sock. This pattern is not hard. Good lord, it's an easily memorized stitch repeat on one round then plain knit on the next, how much easier could she have made it. And the pattern looks great. Here's a better example, since you can't really tell much from that photo above. I love how the stitch pattern pulls the stripes of color into zigzags. I think it is just an awesome match for this yarn. I don't want to lose the simple beauty of the Noro color changes, but I wanted something a little special, something with more pizazz than a straight up stockinette sock. I've finished the heel (did a short row heel instead of the heel flap in the pattern) and I'm working my way down the foot now.