Dunbar's limit

Dunbar's number says our brain maxes out at 150 relationships. This is also a size barrier for many faith communities. (And Mashable notes that it applies to Facebook as well!) Yet I wonder if we don't misapply this principle to communities. If our kingdom networks are more than "church," our 150 includes not just the size of the faith community but our families, our co-workers, our neighbors, people we serve and serve with in the larger world. Could it be that as communities approach the Dunbar number in some aspect -- the raw number nears 150 or the number of relationships that a ministry leader has to manage nears it -- attention and energy gets more focused internally, on the relationships we have to maintain in the church? Might a smaller community be a better target, so there is margin for the people and leaders to extend their networks out into the rest of the world and maintain real connections?