I think it totally depends on what level you are talking about, if you are talking about BN/N I don't see a problem for the most part. Many horses out there roar to a certain extent and many are completely ok doing their job. I only know 1 horse that has had a problem and you could hear that poor horse from the other side of the ring. But quite a few jumpers that do the bigger stuff are roarers, I can hear them while they are on course and ride by. Wouldn't be my first choice for a horse, but really most are completely fine to do "normal" jobs. Of course I wouldn't want one to run upperlevel evening but lower level wouldn't bother me.