The problem is not how they're stored, but where.
I shoot 1,000 images a wedding on average, and put my used CF cards back in their plastic cases they came in, but more importantly, they go in a special pocket of my fanny pack. I'm very careful to zip it up. Pants pockets are unacceptable (per a previous toilet post) as they change aspect when you sit. A zipped fanny pack can be turned upside down and not lose the contents.
And I don't use high-GB cards, either. Just big enough for about 100 photos. That way if you lose a card (or it gets corrupted), you don't lose half the wedding.
And backing up a solid-state device to a non-solid-state device (CF card to disk) makes no sense to me...the disk (moving parts) is far more vulnerable than a CF card. I also don't have the time to be making copies at a wedding, it's far to busy.
