Really, why go to all the physical risk and effort apart from the fireworks in testing?
Doh, I just answered my own question...
But really the answer is much simpler: all disks encrypted with a long random block of data that is stored on a chip, and then just zap the chip with a high energy discharge while rebooting the servers in to the usual memory testing slow BIOS start-up that you always use as you worry about data integrity if your RAM is not checked. Key gone = data gone and in-RAM copies overwritten as well.
Biting the hand that feeds IT
