You have different collections in MongoDb with de-normalized attributes. As you may know, due to its not-join nature, MongoDb tends to encourage repetition of the same value in different collections (de-normalization). In this MongoDb is opposed to a more SQL-like approach where you usually reference only the ID of the value with a foreign key.
Changing the way a CGridView is rendered from the configuration file, or through behaviors specified at the moment it is used, is handy to extend a CGridView without creating tons of different classes for it. I am surprised that this is not in the default implementation, so I made my default CGridView implementation.
If you're working a lot with extensions you often stumble upon problems, when you want to include them into your custom web application, like hardcoded or absolute path aliases or classes extended from core application components, which implement addiditonal features.