Thanks Cliff - yes I am going to check out the Pipes as I've encountered another important flaw in my approach. I've realized that my approach was bad because it meant that the compiler is importing all the view classes into the parent/shell app instead of my ModuleBase derived class.
I understand that ModuleBase is in the Flex framework, but I was explictly using it because I don't have the luxury of importing the Flex UI framework into this particular app as I need to keep the file size down. Compiling my view classes into the shell caused it to be the more file heavy class, which is not what I wanted. Looking back at your Modularity example I think I am now seeing the benefit of using interfaces at the shell level.
I've run out of refactor time for this iteration, but hopefully I can make this work better next time around. Unfortunately, the technical debt here is going to mean my shell swf gets larger as my module view gets larger.
The problem with my design is that I am setting view properties on state instances in a shell swf mediator. Hopefully creating some interfaces with solve this problem for me.
Peter