Couple of things I have looked for when choosing a BOB (or motion controller with integrated BOB) are differential signalling (BOB to stepper driver), and 24V signalling for external signals, not 5V as often seen. Add in attention to wiring runs (keep power/signal separate) and star earthing and you are starting from a good place. I have stepper/spindle/limit switch wiring all running in the same cable chains - although the "power" cables are separated from "signal" by the spindle cooling pipes - and have been lucky enough not to suffer any noise problems. But you do have to work at it to try to head off the problems from the outset - I really hated the idea of having to track down random noise issues. I have also run a ground continuity wire through the cable chains to bond moving bits together (not relying on connections via bearings/ballscrews). I suspect that the proximity switches wired in series are happier with 24V - when I tested them before installation in a series configuration their minimum voltage was around 10V so I suspect even a 12V supply would make them more noise-susceptible. Industrial systems presumably use 24V for a reason!