I have an E-stop at the top RH face of my lathes headstock right where it is natural for the LH hand to slap in a hurry,(and I have used it), but I had never considered the fact that I would be reaching "across the spinning plane of the chuck or face plate." I have a spare E-stop switch so I will wire it in series over on the tailstock end of the lathe.
Thanks for pointing out this danger, now I think about it I realize just how easy it would be to sustain a nasty injury or fatal blow, very scary.