Ok ok, so DVDs/CDs have their issues (yes rewritables have serious issues) I only use Verbatims, and I make 2 copies, though an extra hard drive is a better sollution, as it can read and write a lot faster than ANY flash drive or dvd burner. Flash Drives can become corrupt or infected with viruses, and they break sometimes when you instert/pull them from a computer! As far External Hard Drives, well, just dont' drop them, but yes, they are a great sollution to backup!
There really is no need to worry about the OS, I simply reformat and reinstall in a couple of hours, though imaging is really good, as it's always smart to make an image of your hard drive after you FIRST set it up fully with updates, BEFORE you have any possible chance of being infected by any viruses, malware, or spyware. This way you don't have to spend those hours reinstalling all of your applications and updating your computer software & drivers.
I am wondering, can you image a Solid State Drive? Anyone?
Backup is smart, imaging is really a great idea, but I still religiously believe in making 2 hard copies of your data, and no I don't think he is going overboard with the dual backups. (in multiple formats)