I've played in a Co-ed league for 15+ seasons. Guys dress with guys and girls with girls. League's not competitive, so it's easy enough to share laughs with other teams.
As other's have said, it cuts down on the team comradery. But I think it makes it easier on the women subs. It's one thing to get undressed in front of friends and another to get undressed in front of strangers. For guys like me, I don't care, but for some, this can be very uncomfortable.
Though when we enter tournaments, we've had to share dressing rooms. Simple courtesy applies. Women shower first then guys. Though, I've heard stories about some women who don't give a **** and just shower with the guys. Man that could be awkward if some dude involuntarily gives her a... a salute.
Most rinks around my area now have a women's dressing room. Though usage is dependant on the person. Some girls change with the guys and some in the specified room. Played on a men's team with two girls for better part of ten years, and after a while, everybody got comfortable and nobody even blinked.
My philosophy is it's only awkward if you make it awkward. If you just go with the flow, have a few laughs, and act relatively mature and don't die giggling at the mention of the word pee-pee or tah-tah, things will work out better.