That brings up a similar point which I encountered with a safe not long ago. What happens when Murphy strikes the batteries run down at a most inopportune time. At least with the safe the batteries can be accessed from the outside, and a quick changeout put me back in business, but what about this lock?
At least with a physical lock, no batteries are necessary, and with the Kwikset Smartkey system, locks can be rekeyed in seconds allowing for temporary key sets while you're away (you simply rekey them back when you get home). All mechanical, so no electricity necessary.