I have two bad stories about having files transferred to discs on the road and deleting files from the card! I've become superstitious now and won't do either!!
In Spain, I took my full card to a camera store and asked to have the files burned onto a disc. Well, their equipment somehow lost all the files from Madrid!! I was so upset. I've never tried that again.
And, I fear that I caused a card to become corrupt by going back and forth looking and deleting repeatedly. I lost about 500 images that way once.
They are probably both just awful coincidences or user error of some sort, but will never do either again
