E-STOP Circuit - will this cause any problems?

[birchy]

I would much prefer to kill the power and re-zero rather than rely on software. At the end of the day, it's a safety circuit. I'm not going to add spindle speed control at this stage, however I may add it in the future if I need to replace the motor and/or upgrade to an inverter drive. Latest drawing is attached. Please let me know if you see any mistakes or can suggest improvements!