I've used my cards enough times without any problems to not have any jitters about whether or not the memory has been corrupted when I go to download them. Now if I set my cards near a giant magnet and dropped them in water and ran over them with my car...then maybe.
I used to only use lots of 4GB cards, but recently added a couple 8GB and 16GB cards. My position used to be pretty strong in favor of the "don't keep all your eggs in one basket" philosophy, but I've softened my approach on that quite a bit. In case you are interested, here's why:
If memory gets corrupted it rarely if ever gets entirely corrupted. Memory is arranged in blocks within each card, so a data corruption is typically isolated to one section of a card's memory. So even with a 16GB card if one section of a block were to get corrupted, it wouldn't mean that I'd lose everything on that card. Another thing to consider - let's say I want to take 64GB of cards to a wedding. I can take (4)x16GB cards or (16)x4GB cards or some other combination. The more cards I own, the more I am increasing my odds of getting a bad one, right? It's also nice not to have to change cards so often, or carry as many around.
I still carry around a variety of CF card sizes, but I'm not as fanatical about avoiding larger capacity cards anymore. I've also started capturing some HD video clips for the brides as little bonus "extras" on the final DVD we deliver to them. The extra capacity on the cards is nice for this.