Not really sure this is a good idea. My main issue is with the kids not having the proper exposure to the opposite sex. this may only lead to more discrimination between the sexes and more ignorance. Though the basic ideas (those being that when boys and girls are separated they are easier to teach, and that you can focus on the strengths and weaknesses of the sexes (math strong for boys, literature strong for girls, which I'm not sold on)) are not too bad, I don't think that segregation of sexes will lead to any good. I see instead more bad coming out of this...

My other issue, is they say it is voluntary.. for whom? The child or the child's over protective parents?

I find this to be a horrible idea.