About 150 is the max you can have get together without natural groups forming within the larger group.
Got any references for that? I remember once upon a time seeing an economic study of Spanish anarchist collectives. Things worked OK, as long as the group size was roughly one hundred or less. Same principle.
The congregation we're a part of now is the largest we've been in in my life, somewhere around 700. Yes, it is somewhat fragmented as far as natural groups within it.
Got it from the book Tipping Points...in that he discusses why one religious group always starts a new congregation when they reach somewhere near 100-150 because that's the range where cliques start.