There is a mistaken impression that Camp Hill has all the brainiest children. This is to do with the final score-in being higher than the final score in for the other schools. In actual fact, this may have more to do with the numbers at each school.
For instance, last year the final score-in for CH was 351 (on allocation day), the final for FW was 333 and the one for Aston was 326 or so.
But CH has only 93 places whereas FW has 150, and I have been told through the grapevine (so not a totally reliable source) than the first 100 into FW beat the CH last score, and it's simply a case of they take another 50 children on top of this. That said, I believe Camp Hill over-offer by quite a margin (an extra 30), knowing some of the independently children who have the option of KES will take it instead.
So, were you to compare the two schools at GCSE, you probably should lop off the bottom achievers at Five Ways before you had a valid comparison.
I've also noticed that if parents want Camp Hill Boys, they will 'push the boat out further' as far as tuition is concerned because they know a higher score is required. I hear about children studying for an hour or two a night to achieve Camp Hill whereas my students do 20 minutes maximum. So they may be achieving this score to a degree on the back of hard work rather than natural intelligence, but, then any child/parent willing to put this kind of effort in will sustain it all the way through school so the child will live up to the place they have gained.
But yes, the different schools appeal to different types of children. Where I live we are fairly equidistant to all of them so distance isn't a factor. Generally the more studious, 'take themselves and their studies very seriously' boys opt for Camp Hill. In some cases, however, the choice is made by the parent who wants what they perceive as the best academically, regardless of the nature of their child; this is more common in the private sector where there is a Camp Hill or nowhere mentality.
Five Ways is regarded as the more 'normal' option, favoured by boys and parents who want a superior education but don't necessarily see education as the only factor in their child's upbringing. It probably has a wider social mix, too, by virtue of its location, attracting the 'one-off' cleverest children from Dudley, Halesowen etc. who will have won a place on the back of their raw natural intelligence and often on no or minimal tuition.
I would always advise parents to visit all the schools once in Year 5 and draw up a short list, then visit again at the beginning of Year 6. Try to talk to as many boys as possible (not just the show-off or the really timid boy you happen to get stuck with as a guide) and get a feel for the school. By all means ask others for their opinion but try to ask people who have children and values similar to their own. Judge on what is important to you.
I certainly wouldn't be scared off Camp Hill Boys because of reputation. If it feels right to you, then put it down first. If your son doesn't make the score (and he's had sufficient preparation), then the exam has decided for you that it isn't right for him. But I wouldn't be seduced, either, by the idea it is the 'best' of the schools.
Finally, from an academic perspective, GCSE's are about application rather than high ability or good teaching so your child is fairly likely to come out with the same GCSE's, regardless of which of the KE grammars you choose.