Those are beautiful! My friend who taught me knitting is from Germany and uses a different way to hold yarn than the one I eventually moved to (which she calls the English style). I was not coordinated enough to do her method although it seemed that she had better speed with her way. Those socks are so yummy! I will have to share a pic of the ones I'm working on now...I do different things with mine, all very simple patterns and variations that I came up with over the years, all knit-purl, no lacework or cables. (It's supposed to be relaxing-- not complicated-- something simple enough that I can watch TV while doing it and still keep count).
Your heels are more roomy than mine. And you have a lot of patience to continue the ribbing all the way down the sock! I am usually too impatient/lazy and will sometimes do two rows of ribbing but yours hugs the foot much better I'm sure!
I see you use five needles (four and then the working needle). I use four needles (three and then one working) because it's easier to hold for me. So you use the traditional 64 stitches around and I usually use 56 around for size 1 needles, and 48 for size 2 needles-- but the size 2 needles make a looser fitting sock and too slippery for my taste.
I have not seen bamboo at knitpicks. I'll have to look harder. Where else do you get your sock yarn?