If you are fitting home switches, then in general terms what's the best kind? I'm looking for repeatability here, I think, and the choice seems to be some kind of mechanical switch or a proximity switch. I'm happy that I could interface either kind with whatever electronics/breakout board I eventually select. I have some slight concerns because my 3D printer uses simple little microswitches. In principle these should work OK but I've had repeatability problems with the Z axis switch as you are looking for better than 0.05mm or so and the original switch was not capable of achieving that. In the end I swapped switches around until I found one that gave better repeatability but as a result, I'd like to make sure that the new router, when it gets built, doesn't suffer this way. Could be a critical issue if you are using dual X motors when it comes to squaring/resetting, of course.