latching E-stop button and relay vs. momentary E-stop button and latching relay

Is this an either/or? I've seen diagrams showing both, does it make a
difference which to use, other than it depends on the e-stop button
you might have on hand?

I bought an e-stop button some time ago (can't locate it right now),
and I think it's a mechanically latching button. I wouldn't need to
wire the relay as a latching relay would I? Or can it be wired as a
latching relay for another layer of redundancy of sorts.

For a small mill (Taig, 200 some oz steppers, 100 ipm rapids MAX,
probably more like 50, 20 tpi leadscrews) would cutting the power
supply to the stepper drivers and spindle be adequate? I don't have a
BOB as yet, so I'll deal with lost position and all that with Mach.

Monte