Hi Rene,
Regarding editing projects from the Projects view (if I understand your question correctly), these would not be editable even with Workflow Manager.
Basically, you can edit the template, but when a project is created, it's making copies of the records from wftblTemplates and wftblTemplateTasks and putting them in wftblUserWorkflows and wftblWorkflowTasks tables. We don't have a mechanism for manipulating these entries (and thus the structure of the project) once the records are in the second set of tables, regardless of whether or not you have the AES/WFM piece. The copy is basically done, and then changes to the template are not effected, since the records are separate at that point, so a change in template wouldn't get sync'd to the existing projects.
If you have this as a requirement, I'd recommend contacting support to submit this as a feature request.
Was this your main requirement? Just changing the structure of a Project?