Just for a record: my head size is exactly 22 1/4" which is the upper bound for L and lower bound for XL. I have a friend with the exact same issue, he said he's got L and it fits, so I've ordered L too. It fits me perfectly!
I'm not very amused by the quality of a helmet bag. The helmet smells plastic or paint quite strong. The plastic looks very thin and soft. My second helmet is russian noname fiberglass Z1 copy, and it looks and feels much more durable then G3 and costs much less.
But still - field of view is amazing, G3 looks cool, fits well and is very comfortable. Plus there is enough place behind the opened visor to attach camera safely.