My opinion for what its worth, is....they are too heavy, and they will break your neck when you hit the road. It needs to be made of super lite material, with lots to burn off on impact. An 8 pd helmet at 50 mph weighs about 250pds, weight plus inertia. I believe the design is flawed.
Such as in the race car with Dale Earnhardt sr. Without the hahns device, his head weighed about I dont know 190 mph, with a helmet his head weighed about 1000 pounds, wasnt locked down, snapped his head off the spine.
You would need a head about the size of an oxen to survive that.
My husband doesnt wear when he rides, and I dont push it, because I dont see the advantage. I would prefer he didnt ride on a motorcycle, because I have seen how a telephone pole, a tree or a ray of sunshine shooting through the trees can be a tragic moment. But thats not happening. Thats why I rocked and rolled, before it was cool. I dont know the answer, life is dangerous.