Longest,
I'm in Australia, I don't know the schools you are looking at.
I also don't know if I'm a 'feminist' or not. I look after my children's best interests.
I'm another positive voice for all female education.
Pre-kids I would have said 'oh no, that's sexist or unnecessary, or the world is not single sex so schools should mirror the real world' etc.
We have 3 children - boy, then girl, then boy. We put the children down for various schools when they were little. The eldest (boy) started in a co-ed school and we sent our dd there once she was of school age.
So, our daughter started co-ed alongside her elder brother. It was OK, she was being educated. She learnt to read. She brought home lovely art works.
Once she was in Year 1 she wasn't so happy.. nothing we could pin point. Then her best friend left the school to move overseas.
We had an offer from an all-girls school, starting Year 3.
Spur of the moment, we decided to give the other school a try (on the basis that if it didn't work out we could move her back).
That was the best thing we could have done for her. Absolutely amazing. She is literally a different child. Confident! Willing to try anything, take a risk. That is something worth nurturing in your daughters.
In my opinion, it's not about the 'distraction of boys' (although I agree that this becomes a huge issue for some girls as they hit puberty). It is about freedom. Freedom to just be yourself - total and absolute freedom to learn. To enjoy an education without gender, without having to deal with the complex male-female interactions that occur all the time. Liberating.
Try it and watch your daughters develop.
(My dd has 2 brothers, so lots of male influence and lots of friends of her brothers around. If you are concerned about lack of male influence, enrol her in some hobby with boys. Outside school.)