This has probably already been mentioned somewhere in this thread, but a related advantage to an asciidoc (or similar) approach using git, is that you can more easily take documentation contributions in the form of pull requests. I often find myself wanting to suggest a revision, especially after figuring out how to do something that wasn't clearly explained, but apart from adding comments to the page (which are difficult to put in context), there is no good way to suggest revisions in Confluence.
carl