Diddl - I think you may be right.
I have just returned from a meet-and-greet at the local gs and - this is just ancedotal, mind - there are A LOT of myths about.
I didn't meet any parents whose dc had been at prep schools, for a start.
The group was very, very racially mixed. Way more so than the upper bands at our nearest "outstanding" comprehensive. Which an outside observer might think operates some kind of apartheid when it comes to "ability" banding.
What almost everybody had in common was that they were living in secondary school black holes - with no decent secondary school they could realistically apply to. And many had an experience of the dc being ostracised for being a "boffin" at primary.
Which had led them to apply to a non-catchment gs, some distance from their homes.
Who was missing? Well, I would guess that it was the parents in the socially and economically disadvantaged groups - who just didn;t have the wherewithal to apply to the gs, now that it's an opt-in system.
And there were quite a few self-tutoring parents, and one or two not-tutoring (as in not even seen a paper before) parents.
Tricky re. familiarisation and disadvantage - clearly, the sort of parents who go as far as researching 11+ routes, in an opt-in system, are usually going to then take the step of at least familiarising their dc with the paper. You won't get many in an opt-in system where the dc won't ever have seen a paper.
I have a theory - the whole gs thing attracts a lot of ire, some of which would be more properly deflected at socio-economic questions around education as a whole.
I want to know what happens in comps. re socio-economics.
At our nearest outstanding comp, the ability bands clearly have a socio-economic component. So just having more than 2% on free-school meals at comprehensives does not mean that those children are going to have the disparities of economic and social disability miraculously ironed out in a comprehensive system.
Just to be controversial; I think that the comprehensive system works overwhelmingly in favour of the average off-spring of pushy middle-class parents, who are able to facilitate their childrens' way all through the system.
Anyway, this subject is huge, covers loads of issues and is way beyond discussion in one small post.
And way off topic.