If you do go with 2 copies, i.e. one for the front end, and one for the backend and protect the backend copy with .htaccess using ccbill's script to add users to a .htpasswd file, then you will also want to get this plugin:
http://wordpress.org/plugins/wp-missed-schedule/
for some reason, updates don't work 100% behind a folder protected by .htaccess
That plugin will check for posts that are pre-posted to make sure they show up on the correct day. In the past I had posts that would be a week behind schedule
