If they start killing each other i'll take someout but it's been almost a year and no problems yet maybe some some fin nips during live feedings but nothing major the water is always clean and i do a 50% water change about every 4 days and i feed them non stop . Most of those RBPs are only a year old. except for the big females there some pirayas in there too.
I love it and think its amazing to watch. The only thing that I would do differently is filtration. I would replace the ac's with 2 fx5's or run a large sump, even with the 4 day waterchanges.