I always thought helmets were for wimps, until...
PSP Chicago 2010. I was reffing D3, corner and deadbox. Off the break, standing by the deadbox, i was in the middle of any lane aimed at the home bunker. And i didn't have many places to stand where i could see well. I took AT LEAST 2 shoots to the dome every break. Now, in Race-to-5, that's a lot of hits! I had the worst headache I've ever had in my life, and was so dizzy i could've puked, and was seeing stars by the end of the day. I knew i had a concussion.
The next day, i got to the field a little early and walked around until I found some sort of head protection. The Flex 8 with helmet caught my eye and i bought it. I swear by that sucker, now. I ref'd the same spot the entire tournament and never took another painful headshot again. Flex 8 helmet gets my vote.