ill look into the limit bug when I can get my server back up and running (its currently down due to DNS woes).
As far as limiting per item - not really possible without overly slowing things down. THe replacements are done in one pre_replace call. Otherwise each link would have to be replaced in a loop. If you have 50 links in a thread showing 15 posts, thats 750 replacment calls instead of one!
Hope you dont hold it against me