The difference between High School & All-Stars, besides All-Stars legally being able to do harder stunts, is they have spring floors which I think catches a lot of impact from the jumps and tumbling. Safety is the key with stunting, as in many sports - it can be dangerous and cause broken bones and sprained ankles. Flyers must know how to fall correctly and bases must know they are to always catch the flyer. I think all sports.... higher level high school cheerleading, all-star cheerleading, football, gymnastics, hockey, etc carry risks of injuries but I think the ones listed above are probably in the more top for serious injuries if not trained properly. I was a high school varsity cheerleader myself. I agree with you - one time I fell on my ankle and it hurt for months after.
High School cheer has such variations, as some schools are your more true sideline cheerleaders and others are higher skill...I feel like still though that cheerleading is somewhat still lumped together. Even those who have watched it on ESPN. People don't truly realize how athletic cheerleading can be!