I have found that moving my code to an MVC style architecture cleans up the code immensely.  Granted, it does lead to a lot of boiler plate stuff, but separating things out this way helped me write clear code that was easy to revisit.  I found the series on "Rethinking Xpages" by Pipalia to be a very good grounding in the basics for managed beans with MVC.  I also got a lot of good things from John Dalsgaard's MVC Bean presentations and demo database: particularly the method that he adds to a bean to get a handle on the current bean instance from the class.

Patrick, 

You're big win will likely be cleaner code vs better performance.  To me the best practice is to seperate your business logic from your front end / UI logic.  So I use "pageControllers" to talk to the page and I create classes to work with my business objects (Companies, Contacts, etc) that are more standalone and don't care about the actual "XPage".  That's the best practice in my opinion and a simplified MVC.

By using pageControllers I now create very few "Managed Beans" in the faces-config file.  It's rather nice really.