While customizing the front end with Feather is relatively easy, customizing the backend is not so much. Here are some suggestions to make it easier:
1) Thunder - provide all of the templates for creating any of the backend field types (image picker, single dynamic content type picker, page picker, etc). We should be able to easily create in code what you guys have already done. Also, provide more in depth tutorials on how to create more advanced field types.
2) Include all of the functionality for existing modules (pages, events, etc) that you provide for Dynamic content modules, such as backend screen tweaks, regex validation expressions etc
3) Add a feature for providing permissions at the field level for all custom fields for all modules and pages.
4) Include in depth documentation on all of the configuration sections and what they do on one page. Include sample/scenarios for changing each of the config settings.
5) Move to MVC for everything including backend stuff (I know this is not realistic any time soon however :)