I have one of these on my 3d printer and it is pretty slick and works well with a metallic bed, mines heated aluminum. It isn’t really a solution for milling/routing though because our tool lengths aren’t constant so the Z offset changes with every set-up/tool change. A probe clipped on the tool conducting against a metal touch plate is a good method to use. The touch plate thickness is constant so that can be used to offset your Z axis instead.
@Karl- Do you have a touch plate set up already? I used to have one on my last CNC router but haven’t set it up on the MPCNC yet.