I haven't read the article about the Snell rating, but I also have a Scorpion helmet. I think the biggest issue is making sure it fits properly so the helmet doesn't move on your head. Also you don't want it too tight as that could become a distraction when riding.

An interesting note I heard when I was shopping was to avoid fiberglass helmets. The saleswoman that was helping me at the time said that fiberglass helmets tend to bounce more than plastic ones. Not sure how much of a difference it makes, but it was interesting.