I just think "loaning" a female to a team (or vice versa) for a specific op would be just as problematic, in different ways, than having co-ed units.
For me, segregating is playing to the weaknesses not the strengths. But that is just my opinion, based on my personal experiences from hanging around with the guys. The longer we hang out together, the more at ease we all get. Toss a new female/male into the mix, it gets all stilted up again because no one knows how to react. Familiarity breeds comfort, etc. At least that is how I look at it.
I wonder how it would really be in a tight situtation? In the middle of a mission, in danger, etc. I can only judge it from my non-dangerous life experiences. LOL.