Use YAML to configure and define templates, dialogs and apps. You can define these same items using JCR nodes via Configuration app; YAML is just an additional possibility.
With Magnolia, it is easy to forget configuration changes you make in the tree. When you forget to export them into XML and check into version control, they are not part of the software development lifecycle and get lost. This talk will show how we rethought configuration for Magnolia 5.4, and how we made it easier and more transparent. We now enable developers to provide configuration by file, from their module or webapp, while also allowing them to see every definition that is registered in the system, whether it comes from files, JCR or code. This allows for better teamwork and smoother developer workflow, resulting in more agile deployment.