DS1 did 3 GCSEs early (one in Y9, two in Y10). Consequently, he's only doing 8 GCSEs this year. He could have done 9, but we opted for "private study" as one of his choices, as he chose Art which we knew was a very time-consuming subject. So actually he only has written exams in 7 subjects this year, as Art is obviously not examined in the same way.
For him, it's worked well. He doesn't have a massive amount of exams to revise for now and the exams are reasonably spread out. He's been extremely anxious and difficult to manage at home, so I'm glad that he hasn't had even more pressure on him by having to contend with more subjects.
For DS2 it's all changing, as he will be in the first year doing the new-style GCSEs. He would have expected to do Maths early (top set) and then Additional Maths in Y11, but the school has decided to put them in for both Maths and Add Maths in Y11 to give them the chance of getting a grade 9 which apparently will be higher than an A*, so will look better on their university applications. So DS2 will only do 1 GCSE early (RS in Y10 - no choice) and then all the others in Y11. Like his brother, we have also chosen to do one fewer GCSE than the school's average, so he will end up with 11 GCSEs in total rather than 12, which seems enough to me! I'd rather he got 10-11 good grades, than more lower grades!