Initial impact was slightly above the "love handle" area. I was sliding on my stomach, so the bike must have gone over my back, although I did start tumbling after I got hit. I didnt actually realize I was hit till I stopped tumbling. Thats when the pain kicked in, and I saw the other bike. While I was still tumbling, I remember thinking that I must have caught something on a curb, and thought that that was why I was tumbling. As soon as I stopped, I felt excruciating pain. Similar to getting the wind knocked out, but much worse. I dont know if a flak jacket would have helped.
Every situation is different, and Im not saying you that getting up immediatly is always the best option, but I dont think that you would want to stay down until someone tells you to get up unless you had a potential spinal cord injury.