Self-managed vs. managed condo associations: what's your opinion?

I am wondering about the decision to self-manage versus hire a property manager for our condo association. Is there a certain size association that self-management does not make sense? My experience is that smaller properties (3-10 units) can self-manage no problem and hiring a property manager is not necessary. I have also see much larger associations (~100+ units) that I would expect to hire a property manager. I am interested to hear others perspective and experience on the matter.