After serious consideration, I decided not to go with an Open. 
The bottom bracket they adopted doesn’t allow for a single speed setup. Didn’t want to compromise when the frame cost is premium.
I was attracted to the Open’s light weight, but if I’m honest with myself, I’m not going to be any faster or have any more fun on a bike that’s 5 pounds lighter.
If I was going to order though, it would be an XL. I used to think a smaller bike is more nimble, easier to toss around, lighter etc. But experience has taught me that I enjoy being more centered, feeling like I’m “in” the bike, instead of “on top” of.
I think Open’s recommended sizing is “classic” and not modern for us betweeners.