XHTMLlandmark roles vs ARIA landmark roles

Last July I modified Dojo to support XHTML landmark roles and ARIA roles.  
If an XHTML landmark role already existed on an element, I would APPEND 
the ARIA role to the role attribute rather than replacing it.  This might 
result in an XHTML landmark role and an ARIA role assigned to an element.  
 Now that ARIA officially supports landmark roles that no longer seems 
correct.   The Dojo ticket with further discussion of this issue and 
references to discussions in wai-xtech can be found at [1].

I had defined XHTML landmark roles to be:
banner
contentinfo
definintion
main
navigation
search
note
secondary
seealso

Now that ARIA has many of these should I
1) trim the list of XHTML roles to only the ones not found in ARIA 
(definition, note, secondary, seealso) and still APPEND an ARIA role if 
one of these roles already exists on an element?
2) go back to just allowing one role per element and always replace the 
existing role attribute when an ARIA attribute is set?


thanks,
-becky

[1] http://bugs.dojotoolkit.org/ticket/4828

Becky Gibson
Web Accessibility Architect
                                                       
IBM Emerging Internet Technologies
5 Technology Park Drive
Westford, MA 01886
Voice: 978 399-6101; t/l 333-6101
Email: gibsonb@us.ibm.com