I have been using a first generation AFX for about 2 years now. Last week, I noticed that the top "air scoop" was missing. It is a relatively large plastic piece that appeared to have been snapped into holes in the top of the helmet.
This missing piece does not seem to affect ventilation, which was pretty poor to begin with.
Now, I have an excuse to buy another helmet. I am considering another AFX, the Bilt, MSR, Fly, and a couple of other sub-$200 lids. I seem to beat them up so badly that I cannot see spending $500-700 for an Arai, or a Shoei.