Full Disclosure: I lost about 300 points when the correction happened a couple weeks ago. I then just this morning saw that I gained all/most of it back. I know several times I deleted my posts when (a.) I later found them to be partially incorrect or otherwise inferior, but (b) they had garnered a lot of votes. I'd be worried the OP would go with my answer, and I'm a little embarrassed to be the top-voted answer when it's clearly (a little later) not the best. If I later found my answer to be inferior but had only 0 or 1 upvotes, why bother deleting? It was already getting the votes it deserved! Not sure if this accounted for all my points: Maybe 1 or 2 of my other answers were considered dups and deleted by a moderator.
I certainly agree with Gilles about not deleting "outdated" material. That should be kept indefinitely if not forever. If a would-be archivist wants to improve the tags to make clear the previous version or tooling for which it's relevant, then they are doing a great service.
As for duplicates, I would suggest the poster be given half-value (5 points per upvote) for any gained rep, no matter how much. This is a balance that I believe would motivate people to take the most-desired behavior. It certainly would with me.