6'3" here, and long limbs.
Went for a large.
Wasn't quite happy with the riding position with the standard 350mm seat post at minimum insertion, so bought a 400mm one which I run at 2 to 3 cm above the min mark. Now very happy thankyou.
Yep, agreed they look small but the angle of the seat tube ensures you get enough length in the cockpit corresponding to the height.
My other bike's a 21" rockhopper so I was previously quite used to a stretched out gate of a thing.
Despite initial misgivings (mainly what my eyes were telling me) I'm now pretty much sold that I made the right decision on sizing.