I wouldn't unless for some reason we ended up living in an area where the only state education available was in a school I really really didn't want to send DS to for whatever reason. Lots of violence or something.
But my basic principle is that I think for most children, an educational environment that is more inclusive, not selective by either academic ability or financial criteria, is more beneficial overall. I would like DS to have as much exposure to different people, different families, different social and economic circumstances and 'norms' as possible. I realise that it's difficult to achieve that perfectly, but I feel it is more likely to be achieved at a state school.
I think things like exam results depend more on the individual than the school, and good exam results at a school depend a lot on the type of child who attends the school and the type of parent as well. I am fairly confident that DS will probably be quite intelligent, and he will certainly receive plenty of support.
In terms of optional extras, support, equipment, other opportunities which people often cite as benefits of private school I would prefer to provide those if possible separately while keeping DS within a state-educated environment.
I would also be worried that he might come out talking posh if he went private.
Having said that, I would not say it is 'wrong' for someone else to send their children private. I don't agree with selective education at all myself, and in a fantasy world I would like good inclusive comprehensive state schools available to all.
But that's not going to happen or isn't at the moment so if people choose to send their children to private school I would not say that's 'wrong'.