Yeah... I've had more damage from them using boxes instead of single shipments to be honest. They rattle around so bad because they don't usually protect them all that well. Just steels in a box with no padding, etc.If you order enough at once you might get a box.
However, I will mention that those PET slips help a bit protect the steelbook in general.
Anyone ever done gift-wrapping from them? I'm used to doing it from Amazon.jp but not any of the others. It's an extra 3 Euros as well. I wonder if that would protect them better. Amazon.jp puts the steel in the wrapping envelope and then that whole thing is shrink-wrapped down to cardboard and put in the box.