The problem is that going to separate schools brings back the old problem of "separate but equal", which was anything but equal! I went to a co-ed high school while my brothers went to boys only high schools. I can't see any difference in the quality of education, nor did I ever notice any difficulty on my part related to being in a class with girls. I'd like to see who's doing these studies, and how comprehensive they are, before I say whether they were good or bad.