The vast majority of those posting have never served in any Armed Force, but they purport to know what is best for the Armed Services.
I HAVE served, in combat and outside of it. I knew of several homosexuals that served at the same time as I did. They did their jobs as well as anyone else, and often better than others. I had no problem with them, so long as they were not hitting on heterosexual men (and very few do).
Their blood is the same as anyone elses.
The same arguments were used against integration of Black's into the Armed Forces back in the 1940's. Truman put a stop to that by issuing an order that all black units were to be immediately integrated into the regular forces, and that blacks were to have access to all fields in the military. The military brass predicted that people would refuse to re-enlist, would refuse to serve with "niggers", and that mass chaos would be the result. That did not happen, except in a few isolated cases (and the people involved were disciplined severely).
The US Navy was the MOST reluctant to integrate, not fully accomplishing this until the Vietnam War. The Army got rid of its last all black unit in 1951 (the 24th Infantry Regiment).
Allowing gays to serve openly will have no significant effect at all. A very few will be blatantly "Gay", and they will be discharged for conduct reasons, just like overly aggressive hetereo's are now.