I took the plunge and bought one yesterday at the IMS show here in the Detroit area. I measure 63cm with a round profile, and the XXL fit perfectly. I've never had a helmet that fit so well all over before. It's just a little snug, but that'll break in after awhile. I'm impressed with the whole package.
2015 BMW R9T, 2010 Ducati 1098 Streetfighter S
2009 Kaw 650 Versys, 1967 Triumph 650 TT Special