--
>>> You do want to turn the motor power off at some point, but deciding when
>>> is difficult.  Consider a person whose hand is caught between a tool
>>> (not spinning - no need to be gross here) and a vise.  What you want is
>>> for the pressure on the hand to go away - ie, stop powering the motor
>>> into the hand.  But, you want to be able to drive the axis back a little
>>> manually, which can't be done if the drive is still commanding a stop
>>> (or hold).
>>>
>>
IMHO . power should always be off for E-stop. If you rely on powered items to 
slowdown/stop/be able to move after then you are relying on all these systems 
to work properly. One should remember that E-stop is also for when 
chips/coolant/stuck relays/fried electronics/etc create havoc in the system. 
Power should be cut to all drives as directly as possible. If your design 
creates movement with power off (such as gravity) then mechanical safety 
features must be thought of!
E-stop is not for the convenience of moving the axis away from your caught 
hand, its for stopping the axis from removing your hand from your body.

Cheers
Chris Morley

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