I'm not sure I really agree with the notion that most non-selective schools have 'more than their fair share' of disruptive pupils. I think that is more likely to be true for schools that are generally undersubscribed, but most sought-after nonselective schools will have an intake that pretty much represents the population who want to attend that school.
I think there is a fear-based perception that the presence of children who are not white, middle-class and high-achieving (which, let's face it, is really what people mean when they talk about this kind of cohort) will adversely affect the achievement and overall educational experience of dc who do fall into taht category. But assuming the school is well-managed that absolutely should not be the case. The nightmare scenario is of disruptive children running riot preventing other children from learning and pulling the general academic level to the lowest common denominator. That may have been the case 30 years ago, but no school today would get away with letting that happen. Schools have very detailed target setting for individual pupils and have to track progress very carefully, and manage the learning of different groups, whether by setting or by in-class differentiation. The classroom anarchy scenario is really not one that represents what is going on in inner-ciity schools now.
I must declare an interest, inasmuch as we had a naturally academic high-achieving dc1 who could have got us the DAO dream ticket sibling entry for all the dc. We decided not to go that route because I had reservations about the journey, and also about things I had heard anecdotally about pastoral care and academic pressure in the selective environment. With hindsight, I have no regrets about that decision: high-achiving dc1 did as well as he could have done anywhere; able but not quite so stellar dc2 is predicted A* and A for GCSE, and sees herself as a high-achiever rather than an average-low achiever which she might be in a more competitive school; reasonably bright but very bonkers dc3 I think would not have flourished in an environment that would have highlighted the things she found hard rather than her strenghts. DC2 has several contemporaries from primary who did go the DAO route, either as siblings or just scraping in from the waiting list - none of them are doing significantly better academically than dc2, and I think are possibly less engaged and positive about their school experience than my dc2.
It probably helped us that my dc were at primaries where private or selective school entry was a vanishingly small minority. But there is definitely a critical mass thing, and most of the Islington secondaries that are doing well with a mixed intake absolutely do have children who are able and ambitious, and do well by them. So there is really no reason to assume that any other dc with those abilities and ambitions cannot do just as well in a non-selective local school as they would elsewhere, and possibly have more fun and less pressure in the process.