I've owned my Miata for a couple months now, and I think it's time I took it autocrossing. I know that most events have helmets available, but I think it'd be cool to have my own. I'm looking at Snell SA2010 helmets like this sub-$200 Zamp JA-2.

Is buying an open faced helmet worth the ~$50 savings? I'm concerned that while this will be OK for autocross that it won't work for track days or more serious events.
(Pictured below is the diminutive demon itself)

Edit- Got a full face Solo-Equipped apx helmet in silver. Carbon Fiber tri-weave!