Mach3 vs LinuxCNC/EMC What do you use and why?

[HankMcSpank]

I fail to see how familiarity with the OS helps to run LinuxCNC, since you don't need to make any changes to or with the OS to use it.

Well, the 'puter doesn't build itself, then load the OS itself,then load the app itself - that all needs a human to oversee & if there's a hiccup anywhere, then that's why you need to know your way around the OS ....sure it's not rocket science, but it's a possible time overhead most don't need to incur, because most are using a CNC app running on windows just fine. (or to use the useful Maxim "if it ain't broke, don't fix it!")