So I have been shooting weddings for about 3 years now and I have never had a card issue yet but I know it will happen one day. I only use extreem pro SD or Lexar Professional cards. I have herd over and over to use small cards and that way if one fails you haven't lost everything. My thoughts on that is that if a card is in a camera it is also less likely that it will get lost or stolen than 3-5 cards in your bag/wallet. One time I ejected one of my CF cards a little too hard and it flew out on the ground. So I don't really like removing cards unless I have to. So I guess there are pros an cons to both ways. Since the 5D3 came out I have been putting two large cards (64GB) in the camera and just leaving them in there the whole 12 hour day. If the camera is backing up to both cards I should be okay for the most part. I just herd today of a case where a camera produced some kind of charge that killed both cards so now I am nervous again. Has anyone ever had both cards in there camera fail before and how likely is that to happen? I will be happy when the technology is good enough that you can instantly transfer your images to your laptop quickly and wirelessly. I know the technology exists now but I don't think it is fast enough to transfer large volumes of images quickly.