Hey Alden,
Yes it’s cool to be able to do this by only sensing what the stepper does. I often admire it when someone solves a problem well with minimalistic cost. Generally I like solutions like that.
But when it comes to a CNC machine, I want precision and precision means repeatability, and that’s better with proximity sensors.
Source: Omron E2B Inductive Cylindrical Proximity Sensor Datasheet
Inductive contactless switches will not 