I had a C3-A terrific helmet, but the shape is not for everyone. I guess my head is towards the oval side and I always ended up with a C3 mark in the center of my head. Revzilla, said that it very common, and often is not felt when you initially try the helmet on. I wore my Shoei Neotech around the house for several hours and it seemed to fit well. Thus far not problems with it on the road.
I like Revzlla, and their return policy is terrific as long as the item is not i
installed or worn outside and the tags removed. I love about an hour from them, so anything I order is here the next day via regular UPS. For the helmet I drove into Philadelpha to try several on.
If you do a search there care a number of places that discuss various manufactures and the head shapes they seem to fit. I wish I had looked there prior to the C3 purchase. The Shuberth and Shoei are about the same price.
If you buy the C3, let me know. I have the $399.0 integrated intercom for the helmet. It syncs with any of the Cardo systems I believe. I will sell it inexpensively since it is helmet specific.