Yes that has the benefit of being a "complete" backup. On the other hand you are wasting time and space backing up stuff that does not change. And you have to shut down alfresco while you back up.
Your solution is "simple and stupid" [that's good] so is robust, if you can afford the time, shutdown and disk then go for it. And as and when time and disk become more important you can change to incremental backups of the data that you need.
And you have to shut down alfresco to do this backup since there are certain of the lucene index folders that must not be touched while alfresco is running.
But it's far better to have too much back-up than not enough …