seeker, you pop up on just about every education thread stating that parents are wrong if they:
do no support their local school (ie go to your nearest school, as then everything would even out)
go out of catchment for any reason (as above)
go private
want a different set of subjects/extra curricular activities (although this formed part of your issue with your ds going to the high school - but for other posters, it is not a valid reason to choose another school)
you are massively frustrated by the fact that your dd's school is a reasonable distance away, and you counsel other posters to never consider a school so far away, as it makes life so difficult. you hate the fact that you live in the county you do (educationally speaking) but you do not want ot make other choices (re: work, family, and lifestyle) which wuld enable you to not have the divisive education system you have.
all this is fair enough - it is all your choice (even if you do feel constrained by those choices, such as distance from school). but to then sneer and be snarky about other people making different choices form the ones you made - eg by opting to make that move, or by choosing to go private (for whatever reason), is quite frankly, bizarre.
I have never seen a poster post that their child is too 'bright' for the local state school in the way that you mean. I have seen people worried that their above-average-academically child might be constrained by the choice (or lack thereof) of subjects at the local state school (which you too were worried about, iirc), and then go on to make a different choice fromt heone you have - move, go private, go out of catchment, whatever. but that is just taking action and not being constrained by their circumstance. obviously not everyone can do this (although it can sometimes be achieved by various different means - again, I know htis from personal experience)
I would like you to clarify exactly what you mean by diversity within a school - as has been pointe dout several times, and you have yet to answr the poitns (sorry if I have missed it) - is it 'just' economic diversity you are worried about?