I've been using Joomla for a long time. I have always backed-up my site trough FTP or trough the host-backup utility. For me it was a very frustating work because the ftp connexxion wasn't very reliable. Also it was a hard job to convert my site to a local installation.
Now I found out of JoomlaPack and it's a pies of a cake! Just have to backup trough JoomlaPack, download the created Zip package and extract it to your local folder. Open you website like http://localhost/mywebsitefolder/installation. Follow the steps and in no time the website is installed locally with the mysql database!
Thanks for creating this component developers!!