This is a muddy water issue for me. There are many issues related to implementation of the hardware side of things. I have been recently been party to a brand new 30,000 dollar cammaster router which runs WINCNC which comes Turn Key, drop it on floor level it hook it up (i did the hooking up) and it runs. it seems that all the bugs have been worked out of the machine. I think that most of problems with mach3/4 at this point are actually implementation (hardware) issues. I Feel these new hardware and software systems are standing on the shoulders of The Mach product. At first glance WinCnc looks like a re-skinned version of mach. I am pretty sure it is not but on the surface they do. I have a friend who is ditching his mach3 setup for this
http://www.centroidcnc.com/centroid_diy/acorn_cnc_controller.html He Is using this on his mechmate 4X8 router I am very curious to see how this turns out This will give a side by side comparison. His brother is running a bladreunner (linux) system on his plasma machine.
I am currently dong the groundwork for Mach installation on 3 machines so this is a hot topic for me I am Looking very hard at the CNC-TEKNIC servo motors for all 3 (the CAMMASTER router uses these with belt drives)
Happy Hunting
archie