Does allowing gays in the military compound the problem of discrimination or does it tear down barriers?
DADT will only break down barriers when humanity recognizes that sexual orientation is not a character trait. The character traits an individual possesses is what shows their worth. Dr. Martin Luther King Jr. tried to spread this idea through his "I Have a Dream"speech. The content of our character is what should be valued-not whom we love or with whom we choose to be sexually intimate with.
I think that it will work to tear down barriers in the long run. I do not think that we will see the results of it for a period of time. As mentioned above if we look back in history when African Americans were integrated there was not an immediate difference but over time there was improvement .
There is no way to know the answer to this question at this point in time. We have not yet seen the effects that the repeal of "don't ask, don't tell" will have. We may never know because the repeal's will not be the only factor that will affect the way that gay people are seen in our society.
One thing that we could look at is what happened when African Americans were integrated into the Army (instead of being kept in separate units). It is hard to prove that this action (which happened in the late '40s) either compounded the problem or broke down barriers.
Clearly, there is less discrimination against blacks than there once was. But did the integration of the armed forces help with this? It is hard to know. We will experience the same problem trying to determine what impact the repeal of DADT has.