We'll create fresh WordPress site with Limit Post Revisions Network Option installed. You have 20 minutes to test the plugin after that site we'll be deleted.
A Multisite Network plugin to add Network->Settings to limit, or disable, the number of post revisions and set the post autosave interval.
I based the default plugin values for the constants AUTOSAVE_INTERVAL and WP_POST_REVISIONS on the discussion here: http://wpmututorials.com/how-to/managing-autosavepost-revisions/