I am a S420 user. I think this is a good machine overall. But I want to suggest some improvements.
(1) The machine is heavy. It is very hard to plug in a circuit board. Please bring all the ports to the front and make the electronic modules easy to plug without opening the bottom. Please make it look like a bay. Just let the user insert the module and then connect the hardware.
(2) The middle of the machine bed is not rigid enough. It sounds so empty when you tap it with fingers. This can cause vibration which reduce the cutting accuracy. And this produces more noise too. There should be some sort of support. Some standoffs would be nice.
(3) I once tried to remove the 4 feet and let the machine sit on a firm surface. I noticed the left side of the gantry did not allow me to do this. The wires come out from there! I think this is a bad design. Please let the whole machine bottom touch the bench top. This reduce a lot of vibration. To go further, please prepare some holes and give the user the choice to mount the whole machine to their bench top.
I really hope that you guys will put these into consideration when designing the next version of stepcraft.
Make all of the probes (tool length, 3D, and laser) work with the same logic. Laser won't work with a hard wired in tool length probe. The first two are wired NC and activate on an open circuit. The laser probe is the opposite. All would be the same. In addition, the tool length and 3D should all plug into a connector on the front of the machine.