I will say that I think that if women are to be in direct combat positions, they need to fulfill all of the requirements men do.
Normally, women have different standards on PT tests than men. That's fine. For most people in the military, the important thing is that you're relatively fit, and that means different things for men and women. But if they're going to be in direct combat, they need to have the same strength and stamina their male counterparts do. Provided they can meet those standards (and there are certainly women who can), I see no issue with them serving.