I have mixed feelings on this issue. If its a chance for a better education then I'd say yes, give it a go. I have no doubt that I did far better academically because I got the chance for private education, where the classes were very small and the standard of teaching was high and we were given a lot of individual attention.
However, I'd never send my child to board unless there was no other option, purely because of my experiences.
In my case, I was asked by my parents at age 10 (4th year primary) if I wanted to go (the RAF were paying, so it was full time board or nothing). Of course I said yes. That was the most miserable year of my life. And due to my tendency to grin and make jokes of situations, my parents never really knew how horrible it was. Unfortately this was due solely to the housemistresses we had - think of the sisters in 'James and the Giant peach' both in looks and temperament, and then imagine them looking after your children. Sounds funny now but its not when you're ten years old and they're playing mind games with you. It was such a relief to leave the boarding house every day to see our lovely form teacher, and so awful knowing that night we'd have to go back again to that place.
I moved to senior school after that year and luckily had a lovely housemistress who was strict but kind, and the experience was very different with her. Sadly though, in an all girls school, this is when bullying starts, and if you are stuck at school 24/7 then its relentless when you're the victim. I would hope that now, 20 odd years later, that because bullying has become more prominent in the news then it doesnt get the chance to go as far as it did then and there are better procedures in place to 'catch' it. Girls can be evil witches at that age, without really knowing why theyre doing it.
I don't know how I would have turned out if I hadn't gone to board - how could I? - but I do think my relationship with my folks suffered, although we got there in the end. We'll never be close, but who's to say we would have been anyway - we're not a lovey dovey family but we look out for each other. I didnt know what to do with myself when I was at home - I always felt a bit out of place, because I knew it wouldnt be for long. I also think I was very immature for far longer than perhaps I would have been otherwise, but who knows? Good luck with the decision.