I was in a large performing folk ensemble--we had more than thirty members, including singers, dancers, and instrumentalists. It was great fun but a lot of the spontaneity and freedom that is associated with folk performances goes out the window. On one hand, it has to be tightly run from the top down, but on the other, it must be a coordinated coopertive effort.

Everything must be planned and arranged, from performance materials to snacks. Disagreements, or even just things that no one is sure about, can eat up valuable time--think about it, when you've got a group of 30 or so people rehearsing, fifteen minutes of downtime means you've wasted 7.5 hours of people's time--even worse, you've got to find some other time to do the work that you missed--

Also, with a big group, you have to spend money on a lot of things that small groups can manage out of hand. Transportation, rehearsal space, sound system and set up, hotel rooms, costumes, and insurance, for examples--