Great question. The updates usually work without issue, but it’s always a good idea to have a backup. The Tools/Export function will save all of your posts, pages, custom post types, navigation menus and comments. It won’t save theme settings, plugin settings or your widgets.
For backup, I use and recommend Backup Buddy. It’s an easy to use plugin that works well. It’s also allows you to easily move your site too.
If you want to save all of your settings and you don’t want to use BackupBuddy, you can also export your WordPress database. To do that, log into your web host’s control panel and find the phpMyAdmin section. Three you can access your WordPress database directly and export a copy of it. That way you’ll have a full backup of your content.
If you have any questions or trouble, let me know,
Bill