Sounds okay to me, though I would discard the "parent" and "child" terminology.  Your final paragraph about how the BOD and ED would fit into this makes the whole think look like a more traditional organizational structure than your opening paragraphs led me to believe — more traditional but not necessarily less effective.  To the extent that really encourages bottom-up initiative and leadership and two-way communication and accountability, my guess is it will work well, or well enough.  No structure works perfectly, especially one that involves people

i think this is a great idea.  nice work John and William.  it provides the bottom-up governance we are looking for.  the sooner we start using and refining this structure the sooner we can apply it elsewhere.

one note, the elected rep component of the model is fine for non-Board committees/circles.  however, the current S2BE bylaws state that the Board must elect any new members.  this means that the circles that "elect" reps to the Board can only really make recommendations.  the final decision rests with the Board.  of course the Board can change the bylaws at any time.

someone mentioned concern about invitations and circle membership.  this is an issue we should be mindful of as we implement this model.  large or too fluid circle membership could hinder decision making.  for example, if circle membership is too large then achieving a representative quorum will be difficult.  if circle membership is open or undefined then it will be difficult to define a quorum.  i think we need to concede that authority flows from the (bottom-up) Board.  and for the circle model to work we must remember that each circle is responsible for its work and the work of any sub-circle it convenes.  therefore it is reasonable to expect the members of the convening circle (directly or via the Convener) to have a major role in forming the membership of a sub-circle.

• Interesting idea and outline. What is least clear to me is how the ED fits in. The ED seems to be the link between all the circles and the staff, and
  the ED is kind of an anomaly in the world of circles and conveners and
  reps, being an individual. What are ED resposonsibilites? More exactly: how are ED responsibilities different from those of the Parent committee that is spawning all those children?

• Where does "Mission and expectations throughout the organization are clear (in writing!) right from the beginning." come from? I mean, who writes them and when?

The Organizing Circles look good.  One spot that's been the downfall of a few organizations I've been part of is the relationship between the Executive Director and the board.  The board has to evaluate the performance of the ED regularly, according to criteria that have been carefully established and regularly revisited.