DEFINITE YES! (I can't leave it at just that) I've donated hunters and reining horses to 3 different districts for several years. I've hauled horses almost 1000 miles to get them to competitions for IHSA. I've been asked to donate by some of my formers students, and colleges where I have connections. I've supplied horses, groomed and warmed up horses, I braid all the horses that are shown and have enjoyed assisting the kids as a horse show MOM.
IHSA is a great opportunity for students to try a very challenging endeavor. IT's one thing to catch ride at local shows, or even at A shows, but to always ride different horses at every competition, = adjust your tack, get on and go show the horse. It is a very good test of horsemanship. The owners or trainers provide background info on each horse supplied - what idiocynracies the horse has, or what he needs to be correct...But the competitors don't actually get on until their class is called.
As an owner, it's rewarding to see how my horses handle other riders, and how they compete- do they fall apart or do they do their job and provide the good riders a great ride, and the average riders a good ride... The availability of horses is the limiting factor for a lot of competitions. Every competition could always use MORE horses so they don't have to work as many classes. There are very strict rules and policies to insure the horses are well handled, and the appropriate level of riders are riding the horses for that level. Well trained, sound horses of any breed are generally accepted, but the schools try to keep the appropriate type horses for the classes they are being used for. Typically the Thoroughbred and Appendix and TB X's are used for the hunters, allthough I've seen several exceptional Morgans and Arabians - in some areas like Idaho, the Appaloosa is used for all divisions, and in the midwest, I've seen Saddlebreds under hunter, who did very well. The stock horses are any horse who is capable of the required manuevers for the reining and the under saddle classes.
It's a great way to support young people, get involved with a great intercollegiate activity, and learn more about your horse!