You don't cite examples or your experience. You could have posted here or to the Centroid User forums to hear from others USING the hardware and software:
Centroid Acorn CNC Controller - Centroid Community CNC Support Forum
Centroid Acorn and CNC 12 is more solid than Mach3. Hardware and software from the same manufacturer. The free software that comes with it is very functional. You need to determine your needs and whether or not you need to upgrade.
Besides, do the math, what does the Mach license cost, how much are you going to spend on hardware from another company, and then try to integrate it?
Centroid is not new, they have been in the business for over 30 years and are actively improving the hardware and software.
That said, Mach and other software packages are fine for many folks, Centroid is just another choice for DIY and OEMs.
My .02 FWIW.
Marty