There is the Levitation Project which attempts to port Mediawiki to a Git backend. It was spawned out of pretty much this very same discussion in the German Wikipedia.

http://levit.at/ion/wiki/Main_Page

Larry Sanger (co-creator of Nupedia and Wikipedia) forked it into Citizendium in an attempt to re-infuse a healthy respect for elite, specialist, academic, or otherwise expert knowledge. Hasn't really taken off and Larry Sanger is now emeritus.

Some spammers mirror it.. But that's about it.

If you can work out a good way to share most edits between the forks --- because most edits won't be a source of argument --- then you have a fighting chance.

It could be as simple as mirroring wikipedia but never propagating the deletions. Trying to edit an article would redirect one to wikipedia; trying to edit a deleted article would instead edit the local copy (in the event of the article being recreated on wikipedia at a later date there could be an automatic upstream merge).

This might be a good start. Though you will also want to keep links to the deleted articles alive.

If you took half a second to look through the "New pages" feed, and saw not only the hideous quality and dubious nature of nearly all newly created pages, but also the vast quantity of new articles created every few minutes, you might rethink your position on keeping all deleted articles. Many new articles deserve speedy deletion.

http://en.wikipedia.org/wiki/Special:NewPages

Ok, so only add pages to the mirror that are older than N days or have more than M (non-reverted) edits. Probably you'd also need to have tracking for when page names change. It's not a deal-breaker.

That's a good point. I'll have to think about this.

I started an inclusionist fork called includipedia -- http://www.includipedia.com/ -- though I've not developed it fully.