First of all, congratulations for ten years on the forum, Ducky!
I think that for any major rewrite of a story it is probably best to post it as a new story and topic on the forum. This not only can allow for a clear showcase of how your writing has evolved, but it also can help to confuse readers who might see comments in the topic with reviews and comments about the previous iteration of the story.
I also must admit that I am coming more and more to your line of thinking, Sneak, when you suggest that stories are best to be posted when they are finished. I have had issues with Mender’s Tale due to the posting schedule and how it interferes with the collaborative nature of the story with me and Historian. That is part of the reason that our next project (untitled thus far but it is up to 250,000 words) will only be posted when we are done and Mender’s Tale is done. At the very least, having a detailed plan for long-fics before anything is posted is probably a good idea for some writers.