My head is somewhere between 57-59cm (22.8-23.6" for you American types). I bought a L/XL, fits me better than my favorite pair of underwear. Gansta-pad makes me feel gansta---in regards to soakin up that sweat that is. The visor is my favorite part, but only because everyone complains about it so much, it's hella-tight. Oh and this helmet now makes me look like a unique and beautiful snowflake...but I already knew that! Ha!
Basically, when I was looking for a helmet to raise me to the next level, I was looking for something that gave me a lasting impression. This helmet accomplished that of course. It really stroked me the right way.
Or you can always buy one of those other standard looking flux, xar, xen, hex, kex, or whatever to give you your feeling of solidarity. The choice is yours my friends ^_^.