REMEMBER: A 5-6 point harness system..."induces strong rebounds on the head, owing to the fact that the shoulder straps stop the forward motion of the torso too fast"...as reported from a biomechanical lab study in Sweeden by Ottoson et al in the '80's.
As Panin et al published in Aviation Space Envir. Medicine in 2001..."Futhermore, the frequent necessity of supporting added mass above the shoulders(e.g., crash helmet...) can magnify the moment of inertia of the head"..."the population is at risk for injury due to such forces". Noting that "various methods of fixation of the head to prevent cervical injury are described in the literature."...hence my HANS recommendation !!
Steve Olvey published on this subject in "Neurosurgery" a couple of years back. Many here in Indy may recall that Steve graduated from the IU Med School in 1969, went to Methodist hospital and co-founded the Lifeline System and "matured" the whole area of trauma management for the Speedway...and later CART. One of Steve's recent concerns is gathering GOOD data on helmeted sports injuries to better understand (and thus prevent and/or minimize) not only the acute massive injuries, but also the long term effects of the lesser injuries such as repetitive concussions.
With these things in mind, I HOPE more will look carefully at the equipment that they choose...and be willing to make the necessary investment in their own future.
Have fun...BUT, be SAFE !!!!