Full face helmet saved me from a lot of pain and 20k worth of dental work when I got rear-ended by a drunk while stopped at a red light 5 years ago. Face smashed into the handlebars hard enough to break the chinbar on my helmet,.
Then again, my girl got T-boned by a left-turner last October while wearing full gear, including kevlar pants from Motoport and Alpinestars racing boots. Ended up with a dislocated shoulder, broken femur, broken tibia, 5 broken metatarsals in the foot, (lisfranc fracture they call it) broken calcaneus, broken talus, broken cuboid, and oh BTW the sole of her foot was 3/4 ripped off... It was 2 months before the doc was 100% confident he would not have to amputate. The best gear you can get won't save you from a collision with a vehicle that has 10 times your mass, so assume every cage is trying to kill you.