It sounds a bit like you feel you 'ought' to send your DS to a 'destination' school? That mindset is easy to succumb to in the South East bubble- I know, I've been there.
My son is 9 and late summer born. He was late to take to writing and isn't particularly good at the major team sports.
We lived in commuter-belt Berkshire when he was a pre-schooler and I thought he should go to a destination school (Habs, The Beacon or Caldicott for prep maybe). I thought maybe we'd need to move or board him at senior school so he could go to MCS- or Winchester if he wasn't that bright
.
However, we were unexpectedly shunted out to Dorset by a job move. I cannot tell you how glad I am DS is at an un-pressured rural prep where he spends his time climbing trees, playing cricket and putting on plays. He's so gloriously happy, and that is breeding confidence, motivation and a love for learning. Thankfully, he will be able to go to a fairly laid back 13-18 senior school, where I hope that will all continue.
There is no doubt in my mind he's streets ahead- in his learning but more importantly in his mental health, than he would have been in an aspirational, results-over-journey focused school.
I think what I'm trying to say is choose somewhere you feel he'll be ludicrously happy, rather than where he 'should' go, because the rest will follow.