For mastercam you just need to find the right post processor. It really shouldn’t be too hard, just compare the output to the test file I have linked in the estlcam walk through. I am pretty sure arduino just ignore commands it doesn’t recognize. If you guys get into it a little deeper you can write your own post processor if there already isn’t one. Really we only use the coordinates and maybe pause and resume for tool changes or material flips. Not to many bother with spindle speed control.
The benefit to mastercam is I believe it has a very good feed/speed chip load calculator. The mpcnc will always be on the lower end of there suggested numbers but that information is golden.