I worked at a Montessori school for three years and I had a similar situation to the last post. Our children came from families with many different jobs, lifestyles, religions.
I notice, however, that we lacked ethnic diversity. I am not sure if this is related to the demographics in my area-the majority of the population here is caucasian. however, we do have a large native population here and I always wondered why this group wasn't better represented in the school. My first guess, and this is all it is, is that this is financial. Our school was in no way cheap, but not over the top, but there are many free services for native families. More of these kids may be in federal programs for early childhood ed.
IMO, as a teacher, these programs are a step down from what we offered. As a person who is passionate about giving equal education to all-and feels that our government is failing at this, I hope to have a school of my own someday, and will strive to have scholarship money available for lower income families. A diverse classroom is key to the Montessori philosophy, IMO.