wraith808 - great comparative review. I manage support at SugarSync and you're absolutely correct regarding locked files causing problems. To be successful backing up data files, it's important to follow the software vendor's instructions to create a data backup file and let SugarSync back up the backup file. These products typically have the ability to adjust the frequency of backups. We talk about it here.
The reason for my post was to thank you for helping us improve our knowledgebase. While we do have an article on how to move the Magic Briefcase , we only had a KB article with links to an FAQ about the limitations of our free 2GB plan. I agree with you that it's important information, so we've created a dedicated article on the topic.