A few weeks ago my primary drive began to fail. This was painful because the recovery process exposed lots of rusty plumbing, but I was never worried. I have onsite and offsite backups, multiple iterations of each, using two different technologies (Time Capsule and Carbon Copy Cloner).
I feel pretty good about data loss due to drive failures or boneheaded mistakes.
I don't feel good about the iTunes 11.1 making my media disappear. If not for a chance post encounter I probably wouldn't have discovered the loss for months -- at which time recovery might have been impossible. In this particular case the media files weren't lost -- but iTunes 11.1 couldn't recognize media kind metadata assigned by an earlier version of the app.
Similarly Aperture and iPhoto have been known to lose track of video and images; both have added features to look for orphaned files thanks to past experiences. Users have to know to run these procedures however.
Even worse are sync errors. Apple's Discussions forum are rife with reports of data loss or corruption related to iCloud use. This is bad when it's obvious, but far worse when it goes undetected.
We need new approaches.
We need a utility that keeps a record of deletions, and has rules to notify us of unexpected deletions. That's doable, I'm looking forward to buying a copy.
I don't know what to do about data invisibility arising from application database corruption or bugs like iTunes media kind metadata conversion failure. That's a lot more subtle. Given Apple's poor record of managing these problems (I can think of several things they could do) I wonder if they'll need someday to be legally liable for gross negligence leading to data loss. In the meantime, I suppose we could Voodoo stick pins in something -- or rant in our blogs, which is probably about as effective.