I would recommend keeping a "hard copy" of ANYTHING that you feel is valuable. Servers crash (my school server was just down for TWO DAYS).
I have been backing up to the cloud, but I have a recent backup on my computer also. I plan to do a backup to iTunes every now and then.
I have been using cloud storage forever, but I always backup anything that I feel is "irreplaceable", like my resume, pictures, etc.