Good Flex (3) date / time chooser component

You could solve the problem by using a class factory. Instead of creating instances of new components directly, you would ask a factory class to create the component for you, and based on some criteria (perhaps a static constant value in the Application?) the factory would decide which class to instantiate the component from.

The article and code sample on Wikipedia explains it better than I ever could: Factory method pattern (read on from the "Encapsulation" heading).

Two potential drawbacks with this approach:

1. You will be adding more architecture to your codebase. In my experience the factory pattern doesn't necessarily make code easier to read. Difficult to read code == less reusable code.
2. If you rely heavily on MXML you might need even more quirks to instantiate the components from the factory.

Flash and Flex both use the same underlying rendering engine, just with different front-ends. Flash is better suited for making movies and animations. Flex is better for application development.