The plugin works, but its customization options are too limited and it does not fully comply with the WordPress standards. The "minimum role" option seems to have the roles hardcoded; why not use the get_editable_roles() function for the roles, or better: use the WordPress standard. You should add a capability for managing the order (maybe even per post type) and allow it to be set per role. That's how to WP capability system works.
Also, it doesn't allow you to specify for which post types the functionality should be enabled, which is in my opinion the biggest missing feature.