e-stop sceme

OK. I have Geckos and Bob Campbells breakout board.I have a seperate
50v power suppy. Now I am starting to put the whole thing together.
The first steps are powering everything up. I think the second step
should be arrainging for e-stop. I would like a normaly closed red
mushroom, that when opened will remove power to everything. If I put
relays on the power to the board and the incomeing dc power, would
that be enough. Is it good pratice to power down this way. Do I need
to be concerned with voltage generated by the motors coming to a stop.
I would expect to use this button rutinely to put the machine in a
safe state for tool and part changes. Any advice will be appreciated
take care
Mike Bush