I am a 10 in everything and 9.5 in the Lucas with a little bit of room to spare. They are indeed long in the toebox and a 10 was a sloppy fit with a shit ton of heel slip. But it all depends on how you like your shoes to fit, I'd try them on first.
EDIT: What I mean by "long in the toebox" is this:
In a size 10 (my usual shoe size) Lucas, the shoe fits decently everywhere but in the toebox. There is way too much room. As a result, it doesn't provide the right heel lock. I had to step down to 9.5. So in the 9.5, the shoe fits me a little more snug everywhere but gives me the normal space in the toebox and the right heel lock.