after i posted here i was just thinking about your question. because the thing is, we do let gays serve in all areas of the military (the others you mentioned i am not so sure about) under the clinton "dont ask, dont tell" policy.
so i see your questions is "allow publicly" which makes it different. the thing is, i dont personally care if its public or private. in combat all that your going to care about is how the soldiers next to you handle themselves in combat and how well they can positively dispatch enemy combatants. if you are out there wondering about or thinking about someone's sexual orientation instead of backing each other up, then the question is whether you should be in the military or not.