structured forum threads... & which product
 

Hi,
I am looking for discussion forum software I can customize for use in my PhD studies in education.

I am collecting data on argumentation in online education and need a customizable forum software (trying to avoid writing my own or packages that would require extensive hacking) that will allow me to structure discussion activities for students. What I need specifically:

1. Hierarchically threaded discussion forum. (looks like vBulletin forum satisfies this...)

2. ability to restrict replies. To impose an argumentation structure on a threaded forum, I need to be able to create types of replies to an initial posting. In turn some types of replies may be replied to and some may not. Essentailly I want to create place holders for a tree like structure of a thread, with each node in the tree representing a reply. Some nodes allow futher replies, and some do not. (the tree structure is essentally metadata to the thread, and the reply button would be enabled or disabled based on the metadata and some included logic)

3. #2 needs to be configurable, that is I anticipate creating a instructor control panel to set up the reply types and links between reply types for a given thread (or on a per forum basis...)

4. Students need to access the forum activities I create so that it looks like they are within my university's LMS (Sakai) and I don't want them to have to log into a separate system (though I could live with that). Ideally authentication would be integrated somehow.

5. Some way of easily getting text exports of discussion forum activity for analysis.

All of this was doable in Google Wave and I was gearing up to do it, but suddenly Google is pulling the plug. So I am left looking for other options.

Will vBulletin be able to accommodate my customization needs reasonably, or will I need to do extensive hacking of the underlying system? Which product to I need to purchase?

Thank you for any help or insights,
Gordon