I haven't experienced pre-tertiary single gender education, but in University the course I completed attracted female only students.
That experience was mostly OK, we had a shared educational interest, and everyone was aged 17+ so the dynamic was generally mature; but at times there was exclusion, covert bullying, rumors, gossip, bitchiness, disagreements etc.
Primary and post Primary was co-ed. What I took from the experience was that inclusive education in all its forms teaches an invisible curriculum. Boys and girls learned about each other and how to interact, grew up together, knew each other on a human every day level. There wasn't unknowns about the other sex and I think the balance lent itself to a social order. To generalise, both kept the other in check; at times overt female bitchiness was met with male gruffness and vice versa, taking the corners off each other so to speak. I had a mixture of male and female friends.
I believe I would have had a very negative experience in the single gender alternative.