OP I'm a bit out of touch with some of the boarding preps re my own dc but have helped my godson's parents reasonably recently.
Feel free to PM me.
It depends on child, circs and schools. I went to a wonderful prep, and although I was homesick actually it was the best of the 7 schools I went to. I think my sister would say the same. It still is wonderful by all accounts...though may have gone through a dodgy patch.. Our secondary was dreadful. V famous name, crap and horrible school.
My DH hated his prep school but his parents thought he was incredibly happy there. He wasn't. He was brilliant but slow, dyspraxic and bullied.
We decided not to send Ds to boarding prep, decided that if he boarded at all 8 would be too young. He got into but decided not to attend one of the famous names later, because he didn't want to board.
Those were our decisions. Nit saying they would be right for others. Trying to give the egs to say don't take everything at face value but do trust your gut instinct and your child's happiness is the most important thing. If he's unhappy he won't have the resilient underpinning for adult life. And there's more to life than the UK schools.
Pastoral care has improved even since your DH's day, but be aware there is a condition called boarding school survivors syndrome with some reasonably respectable research around it. I would hope that the improvements mean that the effect is lessening for those in future who could who suffer it.