Equality usually never works by restricting individual freedom. That's ultimately destructive and quickly pisses everyone off. Look at communist societies and how they stultified their culture by attempting that type of forced equality. What I'm saying is that rich kids don't obtain an exceptional educational benefit from these schools. They obtain an exceptional social benefit. That social benefit of being rich is impossible to remove without having a communistic society.
Seems to have worked fine in Finland, and I question how pissed off a population would get when 95% don't benefit from it. As it happens I do want a communistic society, and see this as one element of it. Frankly, my main motivation is having the ruling classes kids in our schools to ensure there's the necessary motivation to fund and improve public schooling. Of course they can carry on networking all they like - but removing their isolation from the working class should make them less sociopathic when they inevitably wield power.