Great stuff-only veered a little of course into airplanes and got lost. Haven't had any issues with my G force other than getting old but I'm used to that hanging around Jerry. Several new manufacturers that I had never heard of but from a safety perspective doesn't seem like you can quantify much past SA2015.
I like what Richard said and tend to agree that in my car I believe I'm more likely to have smaller impacts with my containment seat on the sides of my head than anything. Some incident beyond that I'm likely a vegatable not matter what helmet I'm wearing. Comfort and fit appears to be most important part and then features. Weight could be a factor but no clue how a 2-3 oz difference impacts when there is 3,300 lbs of car/driver to stop. I don't have a pit crew so don't need sound unless there was a way to get a full race broadcast which I would like to alert to wrecks/yellows, etc. A drink tube might be nice to add some XXXX Gold for the last race of the day.

After thinking about my safety setup I need to incorporate wearing my shield down and a balaclava. The issues have been fogging up the shield and/or fogging up my sunglasses I wear. So I'm going to look into that to guide me (I think)-if a helmet helps me incorporate that then it's certainly worth say the extra $500.