Just think it would be nice to not be tied to any specific brand of hardware just because of my choice of control software
Martin, it just doesn't work that way. Mach3/4 is the only software that uses hardware from a variety of vendors. The reason for this is that Mach3 started as a parallel port only, software only control. When they added support for motion controllers, a lot of manufacturers started making Mach3 hardware.
While this made Mach3 much better for many people, this approach has a serious downside. You have two different companies, developing complex hardware and software, that needs to work very well together. But they are developed independently. This leads to a lot of compatibility issues, and lengthy waits for bug fixes, from both parties.
When both the software and hardware are done by the same company, they are designed from the beginning to work together flawlessly, and both are developed together, simultaneously.
Other than Mach, virtually all control software/hardware is locked to each other, unless you look at open source projects.