I tried this a few times to confirm so If I'm doing something wrong....
I'm using version 5 and have been working between a desktop and a notebook. Today I made some big changes, namely compiling SEO within the site. Once you begin SEO, the tab appears next to the View, Edit and HTML tabs. When I was done customizing I backed up my site into a specific folder.
Tonight I transferred the backup file to a zip drive and copied it to my notebook to do some more work. Once the site was imported on my notebook I noticed the SEO tab was gone and some changes I had done this morning did not get saved to the backup file.
I did double check and loaded the .ewp files on my desktop again and those changes were saved on the desktop files from this morning. So, for some reason when I backed up the site using the export option, the software is not including some changes I had made. I would have thought I could have exported the site to a backup file, transferred it to a zip drive and imported the back up file onto my notebook.
I ended up just transferring the .ewp files and folders to my notebook and the SEO tab and the changes I had made were there. So maybe the export option has some issues?