While there are merits to both sides, I'd like to say as one who came out of high school only four years ago that it isn't all that bad - those are the worst aspects. Single sex education also doesn't allow many kids to develop skills to deal with the other sex, either in relationships or simply in everyday life as equals - a boy who never learns to speak up around girls in high school is, I suspect, going to have an even harder time of it in the face of female business parteners.
I also had many more male friends (not boyfriends, friends) than I did female friends- going to a girls' school would have driven me buggy. I really didn't like other girls my age, becasue they were shallow and annoying.
Just a thought.