Yes I’ve served and found that discipline suffered greatly when the genders were mixed.
I served, too (1959-62), and can just imagine the problems that could develop with mixed-sex units. I never served with a woman and it would have seemed odd to me, and the other men with whom I served, to have a female in our midst. Not that we were anti-woman, you understand, it's just that the military seemed to us to be an all-male opeation.