Stay at home mum so zero. Hated private school but was forced to go from reception to yr13. Would never send my kids. So many in my year were forced to go, tutored to oblivion and then completely lost it at uni when they couldn't keep up anymore doing a course they didnt like but parents pushed them down. Either full breakdown or ditching uni completely. Because it was private there wasn't a catchment area so kids were miles apart (opposite side of a county not just across town) making friendships tricky as couldn't meet up. My eldest is doing gcse exams and he loves his school, has great friends all local, teachers far more supportive than mine. I wish I had gone to his school.
My sibiling went to the same school and did very well.uni, high earner.not actually doing anything related to choose not subjects or uni though.
For me, if a child is headstrong and capable then consider it. But don't push the poor things just because you as parents want them to go because their life isn't the same as what you want. Yes you may find they have opportunities there other schools don't get but honestly it's usually over priced trips. My local comp had more facilities and larger range of subjects than the private school I was at. Could have been home in 10 mins instead of a hour which in winter was horrible and if I missed the school bus (teachers overrun!) it was a 2hr walk as the only other way to get home so not home til 6pm which on a cold winters evening was rubbish and exhausting and then still had at least 2 hrs homework a night. We started earlier and finished later so had 8 weeks off at summer which I loved!
Wasn't until I got a weekend job and had friends from the local schools that I realised how much I had missed out on socially, with subject choices and experiences. I haven't stayed friends with anyone from school but I'm still friends with lots from that first job and most are in far better jobs than my private school people.
You still get nasty bullies and rubbish teachers whatever school it is so choose a place your child is happy with, where they can get to easily, where they can have friends local enough to hang out with and where they have a work load they can do unsupported. It's not all about league tables, charts and stuff it's about what school can bring out the best in your child and where they will be happy to grow into their best selves. If that is private, grammar or comp - it doesn't matter as long as your child is happy, confident and capable.