Yeah, I don't think I would start putting any sensitive data like social security number or credit cards on such services without encrypting them, but Backupify only collects data from your public social profiles, and if you are putting such data on them then you deserve whatever is coming at you.
Edit: Check out
This blog post for even more details and info on the free account and why it is free. I'm having a little bit of trouble backing up my wordpress, but that could be because I have a lot of large images on there? Everything else is working fine, and I'll contact their tech support if I can't get wordpress to work soon.
Update 2: The wordpress took a long time to run but it did finally backup. It backed up all files and the database.