Yes.

You'll go to set up something like replication, or maybe CDC, or any one of the other features that check the db_owner and you'll get an error that says nothing like ''database does not have a valid owner" and you'll spend days trying to figure it out until you run across a forum post where someone mentions the database owner not being valid.

Set it to sa. There's little reason not to, it's not escalating permissions since sa is sysadmin (and should be disabled anyway)