I have a fully grown male rainbow cichlid that I wouldn't trust with ANYTHING other than a larger cichlid. He is the most aggressive fish I have ever owned and I have owned a few convicts. I have to say, that I agree with OP on this issue. This fish goes for my hand every time I put it in the tank and it regularly attacks my convict. I too have read online that they are semi-aggressive and are okay for community tanks but after this experience I know that's nonsense. I'm sure you could get lucky and get a relatively peaceful one, but given the behaviour of my current fish, that's not a gamble worth taking.