Imho, never use a pre-formatted solution (such as .local as tld or root pw for root user), because in the future you'll could encounter problems. As bonjour/randevouz used .local for their private addressing creating problems with Panther (
http://docs.info.apple.com/article.html?artnum=107800, and tiger too?) to join domain with .local dns namespace. As refereced by Iana (
http://rfc.net/rfc2606.html), the "world" of .tld is pretty instable and none will guarantee that your private tld it will be used for public namespace (especially if it's "famous" as .local). So i prefere to use real registered namespace also in private envirornment (if possible and if I am the owner of that namespace) or subdomains of that. In other hands, if u need a dns namespace, register it.
Btw, in this matter there aren't a clear true.
Sorry for the OT, have a nice day.