If you were sending your child away to yeshiva, wouldn’t you want to know if they have what I’ve heard referred to as a “Catholic priest problem”?
OTOH, I’ve met many bnei Torah who went to NI and who have stellar middos. I wouldn’t hesitate to send my son for post-H.S. I’m not planning on him boarding anywhere before then – that’s the best way to keep an eye on what’s going in your son’s life on a day-to-day basis.