Hey, good to see another Canadian and from Ontario! Currently, I have a sorority as well, I found the more the better, and the bigger tank the better. I used to have a 10 gallon but it was a "pond like" tank, only 4 inches deep but 3 feet long. The females (8) were always fighting and trying to dominate, but one, (magma) was always queen..
I recently upgraded and now run a 75 gallon sorority....the girls NEVER fight, I have witnessed one fin nip towards a smaller one, so i keep roughly the same sizes. I think this is also due to the stronger current. I have herd bettas prefer still water with not much water flow, however, IMO I believe that by exposing the females to a variety of conditions provides positive benefits to their growth and development, as well as general well being.
I usually shut off the filters when I feed for an hour and give them time to just float. When the filters run, the girls will line up to take turns flying through the jetstream of the power heads, then swim back through the current...they must love it, because there is so many calm areas in the tank....
Love to see some pics!