I love this thread. At its best its full of incredible help, advice and support.
But reading it, as a parent, I would be very wary of taking anecdotes as evidence.
"My friend's neighbour's cousin's sister's daughter (I exaggerate, but only slightly) told me all these terrible things about X school" isn't evidence, it's hearsay.
"I heard that all the children at X school are stressed / unhappy / have mental health disorders / can't keep up with the work / are doing drugs / are having underage sex / are under immense pressure" (delete as appropriate) isn't evidence, it's rumour.
"I've heard that X% of kids at X school did 50 hours a week of private tutoring to get in / stay tutored throughout senior school" isn't data, it's speculation (often entirely unsubstantiated, often fuelled by parental anxiety).
Are there parents at every London selective school who have tutored their child to the hilt to earn them a place? Of course there are. Will that child be okay there and keep up? Who knows, except that family and that school.
Does any school run the admissions process perfectly? Of course not, because the 11+ is far from perfect. I suspect one thing most parents on this thread would agree with is that the 11+ fails to put the wellbeing of the child front and centre.
Are there some children at every selective school across the country who feel under pressure and that they can't keep up? Almost certainly - these are high-achieving institutions and someone is always going to be at the bottom of the cohort (hence great advice on here from @bjmin to find out - post offers, if admissions will tell you - where your child was in that year's group of applicants).
Have you massively over-tutored your child and now, if offered a place at a competitive school, are they going to struggle to keep up? Only you know that - only you know how hard you've pushed them and what level / culture of work they'd be comfortable with.
My advice would be to think back to when you visited all these schools. I don't know about everyone else, but DD and I got a pretty immediate, instinctive sense on open days of where she'd be happy and thrive. Some schools just felt "wrong" for a whole variety of reasons, and some felt very right.
At the end of the day, you know your DC best. This is the next seven years of their life, and will help define the adult they become. Hopefully, in a few weeks' time, you'll all have multiple offers to consider. My advice would be, don't be swayed by league tables (for most of the schools we're discussing, there's really very little between them in terms of results, and as discussed on here at length, research says most children get the same results wherever they go), or what other people might do in your situation. It doesn't matter whether others would kill for a spot at a particular school if you don't think it's the best fit for your child. And try to be honest with yourself about the kind of person your DD is - including their academic interests / capacity / motivation / style of learning - to pick the right fit for them, not the "best" school on your offers list.
On the very first iteration of this thread I mentioned something that we've said to DD a lot when visiting schools: "There's no best school, only the best school for you." I really hope you all find those for your DC over the next month or so.