I just now posted an idea at the Thurston County Democrats blog that I think spans the difference between people that want to stay with a PCO driven organization (where only PCOs can vote) and a membership driven organization, where paid members can participate up to the level they're legally allowed. State law actually defines the role of PCOs, and thereby limits the participation of "members." Though, outside of county organizations and actually only organizational meetings where we choose our executive committees and bylaws, there isn't really anything limiting the participation of a membership.
Votes like campaign services, our yearly budget, spending choices on particular campaigns and endoresments could all be open to members.
I know Thurston County is a bit unique in their PCO only based system, but I'm wondering what other systems for accepting members are out there? Anyone belong to a PCO/member organization? What issues come up with that sort of system?