Are you planning to develop the Customer Journey module? specifically, it is about building Customer Journey Architecture and developing Persona with the ability to add attributes and Persona responses in different CJs.
Customer Journey Map is available at Visual Paradigm Online.
You may learn more about its feature from here
I agree on features of Persona is relatively simple at this moment.
This is pending to enhance as your comment.
I have a question, is the Postmania module available for Customer Journey maps?