I don't know how people come to the conclusion that Livingstonii are that aggressive?
Is it because they haven't kept even more aggressive fish like fullgrown Fusco's, Buccochromis, Tyrannochromis or Champsochromis species?
In my 1300 liter tank the Fusco didn't have more trouble with the livingstonii than the other fish.
But the aggression you will see is more dependent on the particular fish's personality. Furthermore the tank and its inhabitants + hiding rooms etc. are very important. Even larger fish that get in trouble will need to escape to places where the domininant animal can't see them.