Just my $.02 worth. I have an Arab that I raised, from the day he was
born,to do Endurance. I rode him in a sidepull everywhere. Then at 5 1/2
years old, I take him to his first LD and didn't even get to ride around
camp without hooking up a bit. Those bit hangers saved my life! Whew! I
also have a 1/2 Arab, 1/2 Quarter horse mare that rides exclusively in a
sidepull, everywhere, 50s included. Just depends on the horse I guess.
After that experience though I have not ridden my gelding in a sidepull again
- I guess I am just getting too old for that much excitement.