Workflow Best Practice

I am struggling to define a best practice workflow for site development, testing and deployment with Aegir. I have read as much as I could find on the topic, but I don't believe I have found the holy grail. I understand the following to be true:

• Production and development should be on different platforms. I should never be doing development work on a platform that is hosting a production site.
• Once I have a platform ready for testing, I can test the platform with the current production database by cloning the production site to the new platform using my testing domain name (e.g., testing.mysite.com).
• Once testing and bug fixes are complete on the new platform, I can migrate my production site to the new platform using the Aegir Migrate capability.
• Any site configuration that I want to migrate from dev to testing to production need to be put into a Feature. There is no way to move configuration changes from a dev or testing site to a production site. In other words, all configuration changes (stored by Drupal in the database) made on a dev or testing site must be re-implemented on the production site through the UI, if I do not use Features do encapsulate the configuration changes.
• Therefore, best practice dictates that no configuration change should be made that cannot be encapsulated in a Feature, unless the change simply cannot be encapsulated in a Feature in which case excellent notes are necessary.

Have I summarized the best practice workflow correctly. If not, I will appreciate pointers to documentation, blog posts, or other resources that will help me keep my workflow simple and reliable.

Thanks.