I'd say this is pretty conclusive.

The "overcrowding" theory has long been accepted in regards to keeping African cichlids. I really don't see how it's much different with the new world cichlids. Now, I know 29 people will say Central Americans are in no way like Africans. But there are many members here who would disagree, including me.
The bottom line is that it is
possible to reduce nuisance aggression directed towards tankmates by "overcrowding". Besides, we're not really talking aggression, it's more a case of fishes being extremely territorial. If the fishes feel secure in as much that they have enough territory, they won't murder those nearby. Your job as an "overcrowder" is to make them feel secure and happy. If you fail in this area, you will fail at "overcrowding".
Here's what hasn't been mentioned so far that I find fascinating. That is the sheer enjoyment I get from seeing big guapotes
interacting with other big guapotes. And I don't mean lip locking for 45 minutes. I mean spawning and caring for fry, mating displays, competing for food, et cetera. It is a truly awesome thing to get to watch every day. This makes all the hard work worth while.