For storage at home, I want something waterproof - the Canon case is not. Roofs leak, pipes burst, etc. I keep my 600 II (with the hood reversed and foot on) in a Storm im2720 hard case, along with other gear:
I agree with Neuro on cases. I have been using Pelican cases for years to protect gear. Hard shell case, waterproof, and custom foam padding. They have survived dunks into the Atlantic and run rapids with the gear staying safe and dry. It makes no sense to protect a $10,000 lens with anything less.