K, so, the repost function is great, it caters to the lazy and simple minded, but it doesn't take into account the hundreds of deleted threads that were reposts of reposts.
The problem with deleting threads is this, the record is lost and so are the differences between the repost and the original post.
For example, Say I want to post that you can mount your DK flier on top of a mammoth. This is a repost, but I don't know this. I title my thread "cool mammoth trick for DKs". I get some thread titles that relate, but they don't look like what I'm wanting to say. (or maybe they do, I'm making this crap up as I go along)
Maybe I'm a smart user and hit search first for "mammoth Death knight" and nothing close appears. I happily think I'm the one who thought this stuff up.
So I post my retreaded repost of a repost, then it too gets deleted.
If the post had not been deleted, but instead was moved to a forum named "REPOSTS" it would still be searchable and would increase the chances that the poster will see the older post.
I would suggest keeping the repost forum viewable but locked, disallowing replies or new threads. Moderators would be instructed to not delete repost threads, but to always move them to this forum.