I've held of replying to this, but I can't hold of anymore.

Regardless of what people think or say, Art Fennerty brought CNC to the non-computer geeks, and made it accessible. Yes, chances are if Art hadn't done it, somebody else probably would of, but he dedicated the time and effort to do something lots of people said couldn't be done. At the time Mach first appeared, you really did have to be a computer geek to use linux, let along EMC, and Mach provided a familiar alternative.

Linux is now more accesible and useable, but is still an unknown quantity for lots of users. Windows provides a 'safe haven' for those who struggle to do anything more than relatively basic tasks, let alone have to start configuring operating systems. Just because Linux users find things easy to do, doesn't translate to your average computer user even having the slightest idea what you're on about.
This is one of the concepts lots of linux users fail to grasp, and it actually applies to quite a lot of things. My full time job is a mechanic, mostly dealing with diagnostics. If I was to tell you go and check the multi-circuit protection valve on a vehicle, would you even know what it is, or where to begin, bearing in mind lots of drivers would struggle to find the dipstick?


However, the big thing of the future are external motion controllers. Even RTOS's can't match a few dollar DSP sitting churning out pulses. You have one core dealing with generating pulses, another planning motion, one dealing with inputs, one with loading the trajectory, and a few spare to deal with whatever tasks you can think up.
Mach realised this long ago, and added various hooks into it's core to provide support for external controllers, however that is it's current biggest flaw and the reason for the re-write. How would LinuxCNC stack up if somebody suddenly added in lots of interlinked hooks to support external motion controllers?
I'd imagine it would be a core in a similar mess to Mach3 currently is, whereby the simplist of changes can cause havoc with other parts of code.

Re-writes are rarely a good thing, but sometimes there is no other option.

As for what I use, Mach. Simply because I'm not going to start running dual boot/extra computers as lots of other software I use needs windows. Although I'm thinking about setting up KMotion for the KFlop on the new lathe.