I just can't bring myself to order without sizing first! This is a long shot, but if anyone in the Detroit/Ann Arbor area, or even Chicago as I go there for work occasionally, has a 8.5 or 9 in the Hiro or Olfe, I will pay you $10 to meet in a public place of your choosing and let me try on the shoes for 5 minutes. Ok, I'm officially weird. But really, PM me.
I think a full size down from your US size is a safe bet for medium feet. But if you don't want to gamble too much, you can always try their eBay Store for 2nds at a decent price.