My occasional check of the 'new' page shows that most stories fall off the end of the page and are never seen again. Seems overcomplicated to rig a page no one pays much attention to (I could be wrong, but my anecdotal experience over time backs this up).

Wouldn't a simpler metric be how many times a specific user's story posts are flagged? Combine this with a karma threshold for submitting (much like the down-vote threshold) and it seems to me to be a viable option.