We are contemplating this.
taking out DS2 currently in reception but very young and struggling, an dputting him in a priavte school to start recpetion agin in Sept.
We would leave Ds1 at the state school, as he is doing well and happy. It's a good school, DS2 just not ready for it and they can't let them start late or repeat a year.
So, does it work? Do they grow apart, not having shared experiences and references? they are verl close at the moment and I would hate this to cause a feeling of separteness.