I was always worried about placing angels into my community tank because of potential conflicts through breeding. To try and minimise this and give them the most space possible I only put 4 in my tank. I ended up with 2 breeding pairs from 4. My plan of having non breeding angels in a community tank so it would stay relatively peaceful didn't work.
Having said that I am really surprised at the lack of damage to any fish. It is such a deep tank that the tetras shoal along the bottom and get ignored. Their main focus is the other breeding pair but the other pair won't fight they back down so order is restored.
It is 5ft with some plecs and a few tetras. Medium to heavily planted. My temp is normally 26C in summer can be 28C-30C. Last ph reading 6.0, previously it was staying at 6.8(may of been adding too many tannins at water changes) This current ph along with the water changes and the adding of tannins have drove my angels nuts and spawning all over the place, both pairs.
They stay out of the way of bottom feeding fish usually and there is no competition for food because of this. I notice they prefer to feed from the top and will only venture to the bottom when all food at the top has gone. At feeding time all fish get on, it is when the feeding frenzy has stopped they go back to protecting eggs. The other fish at least get a chance to feed without being attacked or warned away.
Having lots of plants in the tank seems to create sections/territories and hiding places so better for the other fish. The plecs are able to stay out the way because of rocks , slat eand wood on th e bottom and can move around unnoticed by the angels. The bottom is thick of cryptocorynes , the corys and oto's can group together amongst these happily and be left alone.
I think as long as there is space to escape if needed, hiding places and no competition at feeding time and aggression doesn't turn into other fish become stressed and damaged then it is fine.
If I started seeing ripped or nipped fins, fish hiding stressed, dying , getting chased around too much and refused access to food I would feel I had a problem and remove the angels .
I'm going to have 2 L128s but other than that I'm not sure. 
