I have kept Tapajos (10 in a 180G), I haven’t kept Mikrogeophagus Altisinosis but have kept Mikrogeophagus Ramirizi.
In my opinion the Tapajos are harmless, their bark is bigger than their bite, if you get my drift. They do display shows of aggression especially when spawning, but very rarely does this result in damage. On the other hand when I kept M. Ramirizi and found them to be quite aggressive, to the point they would take on almost fully grown Pterophyllum Altum.
Of course, the normal rules apply that each fish has its own personality and nothing is set in stone