Also important to note is that HJC does not reccomend the CS/CL lines for competition use, per the rrw article.
I was wearing an HJC AC11 helmet when I crashed rather hard at BHF 3 weeks ago, 2 bike collision and I highsided, head was the first thing to hit the track. I will admit I got my bell rung but I didn't have a headache or any other symptoms, except for a broken ankle and a bruised back. The helmet shows a 2 inch patch where the first layer of fiberglass was removed on impact but no other damage. I have since replaced it with another AC11.
I have worn HJC on the street for 3 years and now at the track, I like the shape of the liner, it is more comfortable for me than any other helmet I have worn. Just keep in mind what you are buying, HJC, like all the other manufacturers, makes low, mid, and high end helmets, the AC series is marketed toward the racing community.