-1 on using URI/URLs, for the simple fact that mobile and desktop devices often don't have a stable hostname and/or IP address. This is a huge area where CouchDB is used, increasingly so, and attempting to tie a DB UUID to something inherently variable on the platform is doomed to fail.
Renaming my PC or phone, getting a new DHCP address, connecting to a different network or changing the MAC address of my NIC should not invalidate my DBs, their "UUIDs", or cause unreasonable problems for replication. -Joan
