I have been using Troxel helmets for over a decade now and twice they have saved me!
My mare and I did the jumpers for several years and one day going over a fence, she took a bad step and tripped and we both toppled into the jump. I got a bad concussion but ended up walking away. We then switched to dressage! No jumps, much safer, right?!
Yesterday we were hacking out through a field, and she took a bad step into a hole (maybe operator error?!) and tripped. Her knees buckled, and I fell and landed on my head again. My helmet actually was warped on one side. But again, I walked away. This time, just some bruises and a little headache.
My mare is such a saint and I wouldn't trade her for the world. She is the most predictable loving horse I have ever known. Accidents happen and I have learned that first hand. Wear your helmet! It may just save your life one day!