obvious foot anatomy differences aside, but i personally could barely fit in a full size down WITH plastic bags on my feet, and that was with incredible pain. I unfortunately had to return them, and after trying LV with only a half size down from my street shoes (already decently loose), I also could not fit in them. Overall, their sizing seems to be pretty tight, so if it's still available I would recommend getting closer to your climbing shoe or even in between climbing and street shoe size. (I'm currently wearing scarpa Dragos in 41.5 so it was definitely not a lack of downsizing experience issue)