Y'know, this is one of those things you just have to try if you really want to know. Bettas have so much personality, and they all seem to have different temperments. For example, I can put my copper crossbreed male in my 20g, but not my blue veiltai Franco. As for females, I had one of my girls in my 6g and she was a total terror - however, the girlie I have in there now that is gentle as a lamb. I just think it's one of those, YMMV kinda things. In general, I would expect a female to be less agressive in a community tank, but again, it depends on the fish.