Cichlids will always be a case of trial and error.
There are no absolutely positive outcomes.
Sometimes a given species will break the mould.Sometimes they will be true to form.
Knowing this, all we really have left is the notoriety of a particular species.In this case the rtm.
Rtm's are a notoriously aggressive species. If you've been involved with cichlid forums long enough you will read many accounts of their aggressive nature.
Can one break the mould? Sure.
Is it likely? No.
If a person were to smoke 40 cigarettes a day,chances are his life would be shorter than if he never smoked.
No guarantees of this,there is a chance he may live to be 100 years old.
The laws of average tell us he stands a good chance of dying younger. Therefore my advice to him would be,don't smoke.
Would I be wrong to give this advice based on a law of averages?I don't think so.
Going by the law of averages with cichlid aggression is all we really have to go by.
I feel the over cautious path is the right way to go with this species. 9 out of 10 will be killers.
As Justarn said keep a divider at hand.