When trying to import a RAW file from my CF card taken on a 5D Mark II the thumbnail shows up, but when I press "import all" a red circle with a white exclamation point shows up on the thumbnail and the photo is not imported. What is this error message?
More cards are a good idea. I would not depend on transferring photos to my iPad without having them still on the card.
When I travel I take enough cards, shoot RAW plus jpg and transfer to my ipad only those files I want to work with or share with others. I leave all files on the card and do not delete them. I keep the cards in a waterproof card case. When I get home I transfer all photos to my computer and two backup disks.