Bernoulli drives and disks are awesome. Easily the most reliable media I've ever used. I have never seen a Bernoulli disk or drive fail even after being kept in a damp musky basement for years. They're also a lot faster than the old MO drives.
If you already have the carts it's a great backup media (assuming you can deal with the relatively low capacities).
Flash drives are difficult to destroy through physical abuse, but I've heard that they're not incredibly reliable overall. Swapped backup hard drives aren't a bad solution (although a pain unless you use hotswapable externals i.e. USB and firwire), but I wouldn't trust old SCSI hard drives for backup purposes.
