I think there is merit and downfalls to both hierarchy and communal structures. All "successful" organizations will find a healthy compromise between the two as they grow and learn, the rest will stagnate and/or disappear.
That being said, I would like to answer Rachael's original question...
"Live in the moment and give what you can for as long as you can, and then get out before the organization and/or you start to suffer."
I serve more than what is considered full time, and I do it because I love the organization, the mission, the volunteers, the potential, and the people we serve. Above all I consider myself a servant of the mission and the organization, I am there to help it succeed and help those that need our services.
I was given a gift by being able to do this full-time and that is in the back of my mind everyday I go to work. I can only hope that as an organization we can provide similar jobs for others with a desire to dedicate themselves to this unique blend of community outreach and bicycle advocacy. While I have energy, I know I won't be able to keep this pace up forever. Right now there are more administrative things that need to be done than their are people, so I pick up that slack and take the blame is something isn't satisfactory. (Why is it the loudest critics are the ones with the smallest piece of the bigger picture?)
As we create more jobs, my job will change but for the better of the organization -- less hours, more responsibility. Hopefully I can grow and change with the position or at least have the forsight to know when someone else would do the job better.
One interesting thing is that I don't ride as much, there are a couple volunteers that jokingly claim I don't know how. I still love to, but to keep sane I need time away from bicycles. So I have hobbies and other side projects for balance. I wrench on cars (OMG!), motorcycles, the house, programming projects, watch netflix with my wife Joe and our three cats, go to the park and play fetch with our dog Apollo. That balance is what keeps me going, without it I think I would burn out. Over half a decade and still going strong.