"How does the OpenACS community see their userbase? Would you divide it this finely or would you paint
broader strokes and consolidate? Would you include #4 and #5 as members of your userbase? "
You're much further along in this kind of thinking than we are - after all we've not made our first non-beta release, yet!
As an outsider to aD, I'd say they've mostly catered to groups #2 and #5. In one sense, #1 doesn't really exist because much of what is core technology in Zope is called "AOLserver" and "the RDBMS" in the ACS world. We (OpenACS) have talked about the need to identify portions of the ACS which really are more core-technologyish, and to develop an API that will allow modules to cleanly register themselves with the system, etc. aD is starting to pay attention to such issues, too, so at the moment we're in a wait-and-see attitude to see what they do for their summer release.