And it'll get quite a bit more interesting with cameras like the AF100; the AVCHD format is directly copyable to, and PLAYABLE from, blu-ray discs. So you can actually plug an AF100 into a blu-ray recorder and the recorder will copy all the data off bit-for-bit accurately as data, but then you can search your archive by actually playing the footage on a blu-ray player. Kind of neat. It's giving you the best of both worlds, tape and data, by doing that. And while I never thought of blu-ray as a practical backup medium for P2, the smaller file sizes of AVCHD make it infinitely more practical. 50GB gives you about five hours of content on one disc.
Optical disc backup is unreliable for long term. I backed up a number of projects to DVDs over the past few years and wanted to go back to some of them and could not read all of the data on a lot of the discs. I had to use about 10 different computers to finally get the data off. I now keep my backups on hard drives with a minimum of 2 copies. If one drive goes bad I have the other. And hard drive storage is dirt cheap these days, costing less per GB than blank BD discs on average, especially the 50GB ones.