I finished my Maelstrom socks, and they fit perfectly. I realy enjoyed knitting them because the leg repeat is only a few rows long, easy to memorize, and each little completed section made me feel like I'd made a huge leap forward. The heel flap and gusset flowed perfectly from the spiraling elements, and the instep offered row by row progress as the diagonal closed in on the opposite side. And for the second sock, the whole thing was reversed in direction, so it was almost like it wasn't even a second sock at all.
How giddy am I over this pattern? I'm going to do something I've never done before: knit another pair, this time in a yarn I picked up at Rhinebeck specifically for this pattern: Blue Moon Fiber Arts Socks That Rock Lightweight, color Rare Gems.
Given my experience with the STR Mediumweight, I can see how Maelstrom's instep knit to the specified gauge can stretch to fit even my 9½ foot. However, I think just knitting the called-for gauge would make the leg a bit of a tussle to fit over my heel putting the thing on, so what I'm going to do on this my second pair is knit the lightweight to my calculated gauge of 7.5 stitches to the inch, and then switch needles after I turn the heel to get the slightly tighter recommended gauge of 8 stitches.
In the meantime, I'm wearing the blue ones. A lot.