: Other answers?
The trouble with such "thought" experiments is that they contain hidden assumptions about human behavior. These include such things as "motivation", "progress", "success" etc.
There have undoubtedly been successful as well as failed collectives. It would probably be more useful to find out the real-life causes. You are setting up a scenario mixing world views. Almost collectives with a free-market value structure - one 'competetively' out-producing another. A collective is a collective. Problems of "dilution" may not be part of a collective's value structure.
I have seen such outlines as yours to defend racism. That Blacks in the ghettoized conditions they find themselves are there because they "lack" sufficient (X) (fill in the blank).