Why not use RAID-5 or some other RAID level? If you do RAID-5 correctly, you should have practically no downtime, still have redundancy and you will have a lot more speed than a Bluray Disc. I have a RAID-5 and after a hick-up the nForce FakeRaid (Ha!) that my RAID-5 used to be sitting on said that one of my drives failed (which it didn't.) The computer would still boot even though the RAID-5 was degraded and you can rebuild the raid while you're using it. Also if you do the RAID correctly like how it would be done on a server, you should have a hot spare in case a drive does die so you can rebuilt it right away. Either that or you can find a RAID-6 controller so you would need to lose more than 2 drives out of n to lose your data instead of just one (this also required 4 hard drives, minimum, where RAID-5 only needs 3.)
Keep in mind that RAID-5 and 6 have reasonable write (take into account that parity data has to be written every time data is written to the RAID,) but reads have performance similar to RAID-0 because it ignores parity (unless you're running in degraded mode.)
Personally, I've been very happy with my 3x1TB RAID-5 and when hard drives weren't incredibly expensive, I would recommend 3x750gb WD Blacks which would have costs about 240 USD (before WD got flooded out,) for 1.5Tb of redundant storage (and relatively quick compared to a single HDD or a Blu-Ray Disc.)
I just find it easier to search my files on a file system, not a cabinet with labeled cases. To each their own. Also there is no redundancy to Blu-Ray discs. Once it is gone, it is gone. I can rip a drive out of my raid, throw it out the window, and I would still be good.
Edit: Additionally, if you do a RAID-5 of 3x1Tb drives like I did, you could get a 2tb external drive as a backup of your raid, then you have your data in a position where you would have to lose 2 drives in your raid and your external drive to lose all of your data. It can happen, but the point is every time you add redundancy you're mitigating the chances of everything dying all at once. At this point though, you've lost 3 of your 4 hard drives, something that won't happen if you replace things in a reasonable amount of time.
Jeez, if I fling an hd at the wall, I could loose all data, if I fling a bluray disc at the wall, it will probably survive. For the cost difference, I still think bluray discs are much safer. You can put it anyway you like, but it's cheaper, and safer than many, even much more expensive methods. I'm poor, so I like this method!
Actually, the HDD platter would most likely survive, your case wouldn't though. Theoretically you can recover data if you do this. It takes a lot of acceleration to displace data on magnetic media (something like 100G of acceleration, some nutty number like that). At least HDDs can be written over multiple times
quickly.