It's nonsense to say Reeds is a fallover for St Johns and St Georges.
In fact:
RGS - number 1 (out of these) by far - 25% to Oxbridge, 93% A/A at GCSE, 97% A/B at A Level
St Johns - negligible to Oxbridge, 60% A/A GCSE, 80% A/B at A Level
St Georges - negligible to Oxbridge, 70% A/A GCSE, 80% A/B at A Level
Reeds - negligible to Oxbridge, 60% A/A GCSE, 80% A/B at A Level
St Georges is co-ed so results not directly comparable.
Reeds has a reputation as a 'safety' option, but their very good results have allowed them to reject more pupils in recent years, and presumably this trend will continue.
I think St Georges probably has the brightest pupils (co-ed, quite a good position, a little arrogant IMO), I'm just not convinced they handle them as well as the others.
You do I believe have to do quite a lot of sport at Reeds until something like the fifth year, so even if you are not sporty, they still make you take part.