Hi,
I use Mach4Hobby and have done for eight years.
I use it daily for making small parts (for automotive instruments) and isolation routed circuit boards. It is not industrial, but I do make a living from it.
I have also done some retrofits to various machines, a couple of plasma tables, a lathe and most recently a guillotine. My experience is that Mach4 is quite flexible and useful
for retrofit purposes, and is very modestly priced relative to genuine industrial controllers.
Is there a particular feature or operation that you need it to perform? Mach4 is well suited to and pretty much ready to go with up to six axis mills.
Craig