To add to the anecdotal evidence, I have been using high end Sandisk CF cards for 11 years and have had zero failures or problems. They work well for me.
Bill
I have shot >55000 images since I bought my first DSLR (the actual number is significantly larger, but these are the ones that I have not deleted. Many I ought to have deleted, though.).
I have a mix of old and new, small and large, expensive and no-name cards.
Out of those images, I know of exactly 2 that came out corrupted. I believe that was a Canon camera software problem (the camera became non-responsive), but you never know.
This experience has made me very relaxed about memory cards. I have the feeling that those who report about massive problems with memory cards either:
1. Have had bad luck
2. Do something to their cameras/cards that I do not
3. Are examples of cherry-picking (one is more likely to share ones experiences if one has had problems that if not).
I am _not_ claiming that no-one has ever had any problems with memory cards. But I am suggesting that internet forum polls may not be a robust source of information about how frequent this happens.
Now, If my photography was highly paid once-in-a-lifetime events, I might want some redundance "just in case". I have reasonable redundance for my long-time-storage of images as I have experienced one harddrive failure in my life, and life is too short to generate personal statistics on 10-year-life-expectancy of hard-drives containing _all_ of your images.
-h