I had pairs together without problems. I would not risk to house two males together. I also had two females together, but they were fighting because of their favourite basking branch, so I separated them.
In my experience, my adut pairs would live together, but would then be completely uninterested in breeding. Keeping them separated and then introducing them worked better. Unfortunatley my male was never interested in doing the deed.
As stated above, it depends on the individual animal. Some are agressive towards anything else in their "space".
My juvi male oustalets did good together for a little bit but then did start becoming aggressive so I did seperate them. I know somebody on these forums told me in Florida he documented several males/females living in very close proximity, basically a group living together in the same tree with no issues. I can't speak for females/males together though.
I have a beautiful male oustalet cham can you guys post me pic of their housing cause i need to get him his big boy cage soon so i need some ideas of what you have and in them so i have ideas of what i'm gonna have to work with when i build his cage!!!