and I am amazed at how much the belts flex and the body moves around in the cabin. Much more so with 3 points. These movements are so violent, that I am certain injuries are occuring even if the body didn't hit a thing.
The only concern I do have is that I think there is a greater risk in neck injuries because a harness secures the body tighter and the head/neck receives a greater load. There is no HNR at play on the street, but on the track with a helmet and a HNR like a HANS, you are MUCH safer than being in a 3 point which is just improper. I'll take my chances with a roof collapse over a 3 point.