Hi Nick

The answer is for a DIY machine that you are the only user then it’s what you feel happy with.

My mk1 just used the estop pin on the breakout board and relied on that to stop sending stepper signals to the drivers and tell Mach3 to stop sending signals to the breakout board.
Had no issues for years with that setup.

For mk2 or 3 (can’t remember!) I made a proper control box with a safer estop circuit and better overall functionality. I have a master relay (not a proper Pilz style but the same principle) that has multiple outputs and one of these drops power to the contactor which controls the linear psu. Other outputs drop the self latch and drop power to the spindle relay which controls the VFD run/stop logic signal and drops the estop pin connection on the breakout board so Mach 3 knows to stop. My drives don’t have stall detect etc so my only reason was a bit more piece of mind. I’m reusing most of this for the current mk4 with the main difference being that axis limit trips are going to be soft stop limit events and not part of the hard estop circuit. I think this last part on limit trips is Dean’s approach and having tried it out on one axis I agree with him.