I am no expert on research pieces but I must wonder at yours. Surely you should be trying to find out the truth? You can't do that if your mind is not only already made up, but you have expressed that decision to those you are trying to get opinions from.
True research into opinions is only possible if you hide your own.
You are also guilty of muddy thinking. You are confusing "pushy" with "affluent". I am sure there is a correlation, but they are different things.
I will make the point that I am pushy, NOT affluent. I taught my daughter myself. If many pushy parents are affluent, well, that is how they got to be affluent! Being affluent in itself is not particularly an advantage here. There must be a few affluent parents who are incapable of learning (and thus teaching) a test meant for 10-11 year olds, but how common is 2 totally thick parents, making lots of money with a bright kid? This is not quite the battle of rich kids vs poor kids you would like to make it.
I pushed hard for my daughter to do well in the Wandsworth tests (Verbal & Non-verbal). My hope is that she passes to get into a school with a good records of success with both gifted and non-gifted children. Admittedly I suspect just about ALL of those kids have pushy parents - those who didn't get in via the test had well pushed older siblings or lived in a catchment area the size of a postage stamp. I define buying/renting property specifically to get a child into a school as "pushy".
Should a child go to a particular school because their parents are pushy? When it comes to passing a test the answer could well be yes. Consider: to pass these tests a child needs a combination of intelligence, determination, and preparation. The relative quantity of those ingredients is flexible, but those are EXACTLY the same qualities the child will need to get the most out of a demanding education. The intelligence is the child's alone, but the determination and preparation can, to some extent, come from the parents. I say "some extent". You can lead a horse to water, but you can't make it drink.
What if your plan was carried out? Well, first it wouldn't work. There is no way that parents won't find a way. My daughter's school DID carry out some such plan by not informing parents till the beginning of the autumn term when they were forced to give out Wandsworth literature that mentioned it. The result? I gave my daughter a highly stressful crash course on reasoning tests the moment I found out. She went "sick" rather a lot during that term, up to the test. When she was there she was probably to tired to do much learning, and as for her homework - well I did a lot of it. If only the school had informed me before the summer holiday's! All then would have been different. I wasn't alone in preparing my child during that term. In an effort to stop us the teacher responded by telling all the children involved that they had little hope of passing. Needless to say THAT resulted in rage from the parents and children being told not to listen to or trust their teacher! Mercifully the headmaster retired that term. The new headmistress has promised that things will be different for next year.
The point? Us parents will do whatever we think is in the best interests of our children. We are not interested in "justice" for other people's children, or the happiness or social theories of teachers. There is a scrum for the best schools, and those who push hardest get in. You could possibly persuade some parents to form an orderly line but they will be the fools. There will always be enough parents who find a way to shove their kids forward to leave no hope for the polite ones. Your plan will just swap kids with pushy parents for kids with parents who are both pushy AND devious.
In the second place it would not be necessarily a good thing if your plan worked. What if you did get the bright kids with unsupportive parents into these schools? Any teacher will tell you that without parental support their task is hopeless. Are you advocating removing these kids from their families?
This is just another argument of whether parents or authorities should be in charge of shaping children. Parents are a long way from perfect, and it is a lottery, with some children getting better than others, but can you propose a better solution? As best as I understand it the idea of the state raising children has been well tried, and the results are discouraging. Current thinking is that except in exceptional circumstances kids do best with their biological parents.