I have a (shy) child at Fortismere and am friends with parents of kids at other local schools. All kids at some point may need a tutor. I think there are lots of reasons - confidence, too shy to ask questions, dyslexia, advanced etc.... and I know kids who are heavily tutored in other schools. I don't think Fortismere is worse for this at all.
I have a very (academically) average child. My child thinks the teachers are great. There isn't a problem with supply teachers as far as I know - certainly not in core subjects nor the ones my child takes. But of course, there maybe in other subjects? My child enjoys the lessons and feels very safe there.
I do get what a previous poster said about it having a 'uni' vibe. I think that was quite astute. But I think the way they teach encourages discussion and excitement about the subjects.
Although it is relaxed about many things - at the same time it seems very strict about important stuff, like behaviour in lessons - which I like.
I'd say that what makes Fortismere good is the quality of its teachers - and the lessons themselves.
In terms of pastoral care - hmm, I think it could be better. But that said my child is happy there and doing better than they would at other local schools. They started knowing no one but have made great friends.
I do prefer APS because it feels very organised but Fortismere does get good results, year on year, so they are doing something really well -
I guess it comes down to individual children - Archers seems like a good school - you have a dilemma - but between two great schools!