More sizing info
Just adding to the sizing data, since I wasn't sure when I was ordering: the size Large (labled by Gore as "9.0-10.5" and "EUR 42-44") just barely fits over a Pearl Izumi X-Alp Seek IV size 45 (US 11.5), a MTB/commuter type shoe. My first thought when I started pulling them on was that I would need an XL, but it covers the shoe and the velcro meets in the back ok, so I think I will stick with the Large.
For my SIDI Dominator IVs (which unfortunately aren't marked, but must be either a 44 or 45), a lower-volume "cycling" shoe, the size Large also will work, but is a little on the loose side. I would guess that a Medium might work for those as well, perhaps better.