I agree with Clive in his post above (Hi Clive !)

However my personal preference on big powerful machines is to have the home switches inside the boundries set by the limit switches, and have the limit switches trigger powering off of the drives. Also to have the limit switches within the boundries of mechanical stops that limit travel before ball screws over travel.

With a big servo driven machine like my CNC Beaver Partsmaster Mill, or the Traub lathe I rebuilt last year (now sold), the servo drives are a few killowatts, so if they run away damage WILL be done without limits.

However that said, my CNC Plasma Table is set up sharing home and limit switches driven by Mach3 - it's how the chap who originally built it made it, and it wasn't easily altered when I re-built it. But the drives are steppers and only Nema 46's so in the worst case if it runs away not much breaks !