I agree its VERY creative thinking (I can't say I would have ever come up with that idea of Powerline Networking), but there are some potential problems with this idea:
-Most fireproof safes are designed to protect paper and similar materials, not computer media. There are actually special fireproof safes designed for computer media. Of all computer media (CD, DVD, Floppy, etc.), I'd imagine Hard Drives (including those contained in a NAS) are the most sensitive, so hopefully the safe he purchased is rated to protect Computer Media.
-I was going to say this solution doesn't proect against theft (including theft of the safe itself), but looking at that particular safe he bought, its pretty big, heavy, and uncrackable, so I don't think that's too much of an issue.
As a side note, Iron Mountain is about the cream of the crop when it comes to online backup solutions, but there are others that are liekly cheaper. I use
www.ibackup.com and have been very happy with it......I wonder if the author of that article ever considered other online backup providers?
NONE THE LESS, very interesting and creative!