User blog comment:Jenburton/Coming Soon: Message Wall in Labs/@comment-737801-20111024221751/@comment-168424-20111027210339

Can't reply to a reply... Grrr.

888th Avatar, the main difference between talk pages and Message Wall is that each post and reply on a Message Wall is effectively a new page, so it stands a better chance of both slowing down wikis and clogging the database.

Wikia should enable this feature on at least one really large wiki (25K+ pages) with a decent amount of activity to see how it really affects performance. More details on this issue have been put in posts above.