For what it's worth, you might be interested in the Buddypress
community discussion concerning the integration of MediaWiki into
Buddypress. See
http://buddypress.org/community/groups/third-party-components-plugins/forum/topic/mediawiki-edits-bp-activity-streams/
It appears that two Buddypress websites have already done this type of
integration for logins: CUNY and Chembook, both of which are featured
on the Buddypress examples page. It seems that the CUNY programmer
also created a plugin to integrate Mediawiki activity streams with
Buddypress, then abandoned the effort (although it's still listed as a
MediaWiki extension).
I recognize that all this is rather far afield from your immediate
objectives to get GDSR 2.0 out the door and get your business
successfully launched. Nevertheless, I hope you will keep wiki
integration in the back of your head. Meanwhile, I'm very excited to
hear that Buddypress integration, although a pain, is one of your
priorities. I'm also pleased to hear that you're striving for more
Apple-like simplicity in your user interface. To the extent that you
can create many features but hide the complexity under the hood, I
think you'll expand your user base.
I'm eagerly awaiting your integration with Buddypress.
--Jim