Scope and compatibility for DITA 1.1

While discussing one of the DITA 1.1 issues, I realized that I don't
have a good sense of how far we can go before something becomes less
desirable for a minor release. Are any of these changes less desirable
than others if we want to make "modest" improvements to DITA?

  
Add new attributes to an old element

  
Relax content for an element so it can contain previously
disallowed elements

  
Specialize new elements off a pre-existing element

  
Create brand new elements

Chris