The mix in my tank (2 kribs, 2 bolivian rams, 2 blue rams, 2 keyholes) seems to work ok at the moment. The kribs spawn every couple of weeks and chase other fish off, but thats about it. Probably the exception rather than the rule though.
They completely ignore my cories and the neons keep away from them. The danios and rainbows swim in the top level and dont get bothered by the cichlids at all.
Jon