The Defender lens case has a sturdy zip to keep the lens in place and is extremely well padded around the body of the case. The Canon lens bags are very flimsy in comparison and offer virtually no protection in the event of dropping the bag. I haven't tested it (!!) but from its construction I would imagine that a lens in the Hama lens case will survive a reasonable drop intact due to the padding and build.
|Canon 70-200 f2.8IS lens case side by side with Hama Defender|
Camera lens case -
DSLR camera bag -