Are you talking about the peacock stirrups that have a big thick rubber band on them? Or the Western stirrup that comes off the fender?
I used to volunteer at a therapeutic riding center- we used the Western Breakaways. They were very nice. They acted as a regular stirrup, can't really tell they are different. If a rider fell, (which never happened while I was there) the stirrup was designed to rotate and come off.
Spent a whole hour today laying in a pasture, waiting for a sparkling vampire to show up. Alas, I woke up and looked over, only to find a mound of horse crap. Sigh.