Oooh, what a lovely dilemma! Congrats to your DS.
I have 3 DC, one at a local SE26 state primary, one at Newstead Wood, and DS is in y9 at DC. (In the interests of transparency 
"After the ST Olaves 6th form fiasco I wouldn’t touch them with a barge pole tbh.
I know people whose children go/have have been there and they have a shocking reputation re pastoral care."
This is - unfairly in our experience - the reputation St O seems to have, and when we were lucky enough to have to decide between St O and Wilson's 3 years ago, the online reputation of St O as being purely an exam factory did give us pause. But DS really loved St O, and the commute is easier, so we went with it.
He was quite an anxious child, and found the transition to secondary school quite overwhelming. When I contacted school about it, they could not have been better at offering support/ strategies/ follow up. There have been a couple of other incidences, and they have been very professional , and I was (probably unfairly!) pleasantly surprised. I was not a fan of the previous head, and since he left there have been some very welcome changes such as the well-being week, and a no homework week once a term so boys can concentrate on extracurricular interests.
DS is extremely happy there, after having been spectacularly unhappy at his primary.
That said, if I had a full bursary from DC, I would bite their hand off. The 'new' (not so new now) Head has been committed to raising the academic results, and I am envious of their choice of extra-curricular activities. I have a couple of friends with children there (y7, y9 and y11 between them), and they are extremely happy with their experiences there. None of the boys are sporty - two are very involved in the school orchestra which has taken them to the US and across Europe.
You will know which the best fit will be for your son and your family: best of luck with your decision.