At BGS the kids take the GCSEs ONLY if they are going to get good grade ie A/A*. And then it's only in some of the subjects eg, maths for the top sets, the 1st language taken from yr7, some science.
My dd is taking maths early and thought, at that point, that she would never have to do maths again. Wrong! They do further maths in year 11!
With BH, I think that there is a drive for kids to go into yr11 already having got the 5 A*- C. If some of these subjects have already been passed a year early then it gives room to improve the others. This is already being done at other comps in the borough.
And controversially, has anyone actually seen the GCSE papers these days? Let's just say I'd like to see the same batch of kids sit O levels and then compare results.