Historically the main reason for why women have not been allowed to participate in armed combat has not as much to do with physical strenght, as to their reproduction abilities. If 40% of the male population in a little isolated village died in combat, it would slighty affect the village's birthrate for several years. While if 40% of the village's female population died in combat, it would affect the village's birthrates for generations, and may actually even threath its very existence. At least in a pre-birthcontroll pills, pre-automobils and pre-penicilin era, which in most parts of the world would mean going only 100 years back in time or less.
That is not a valid argument in modern society, taking into consideration how low today's birthrates and infant deaths are, but changing more than 1000 years old traditions and ways of thinking are not something that can be done in a day. Personally, if a woman wish to join military and participate in armed combat I do not see why they should not be allowed. It's not a job position many women usually apply for, partly due the lack of support received from friends, family and the rest of society. So if a women is so determined that she's willing to defy tradition and go ahead and choose such a path despite knowing the hardship she will meet in her work from family and colleagues alike, I think you'd be better off with her than without her.
Here where I live men are forced to join the military, regardless of their personal opionion on the matter. In the choice of entrusting a mission between three men who lacks motivation, hates the military and are just waiting to find a way to get home, and a woman that fought her way to the system just to get this possibility, I'd go for the woman. If nothing else than because the hardship a woman has to go through to get even a slightly significant position in the military will have made her much tougher than the avarage forcibly recruited man.
Just my personal, humble opinion of course. ^^