Mate, Peer Guardians only function left in respect to Utorrent is blocking leechers.. You can use it to block leechers whom you don't want to upload the file to.. Let's say you released a torrent and it is heavily leeched, 1 leecher is consuming all your bandwidth and not uploading back at all.. Then only would Peer Guardian be useful..

Azureus has this feature built into it.. known as 'kick and ban'..

With Utorrents updates after 1.7.3.. You don't need Peer Guardian with it.. It is very secure now.. Make sure you have the latest Utorrent version and enjoy..

Peace.. Hope its clear now..

x|D