Your Valence instance can listen on more than one port
Since the official Valence 6 release in September, many sites currently using a prior version of Valence face the somewhat daunting task of getting users to change their URLs to the new instance. If you're not using some sort of an alias or permanent redirect in Apache — meaning the port number for your Valence instance is part of the URL — then you're looking at potentially hundreds of users needing to update their browser bookmarks to point to a different port.