Hey Bill,
An idea for a workaround that many people have and had in the past is to put the controller on an UPS. However there is still a problem with it, as described here: The UPS is able to signal to the controller that the power has gone but yet there is no solution how the nut daemon would trigger “pause”. At the moment it is easily possible to let the UPS trigger the “estop” mode on the controller, but that means loosing all positions so this does not help you. However it ensures stopping the milling motor and halting the machine’s stepper motors movement very quickly at power loss, which would prevent milling bit or workpiece damage.
I’ll definitely have a look at it one day, but I don’t run this controller (though I own one) and have no time at the moment!