Another question that asks it self is who does the dirty jobs. And I mean that literally. For anything resembling a modern society to function you need people to unclog your sewers, shovel garbage and get their arms up to the elbow in grease maintaining stuff. Does your colony outsource all these jobs to out-of-colony businesses? In that case there is a potential point of failure. Does it make colonists do it on their own? How many 150 IQ people want to make a carrier of unclogging toilets? Again a point of failure.