Turns out that REI carries the Vibram
FiveFingers (yes, I know you can order them from Vibram, but I have
unusual shaped feet so I'd like to try them on before being committed)
I stopped by the local store and tried on the
45s (USA 11 1/4), but they're too big even though I normally wear
12s. Unfortunately, 45 was all they had in stock, but I ordered
a pair of 44s. Will update when I've had a chance to try them.

Based on their measuring instructions, I ordered a pair of 44s. As we have the same size (though differently shaped feet, your experience is good news.