The Mesa Boards from America are good CNC-Boards as well. But it runs merely with linuxcnc, and the developer of the boards is often in the LC-forum.
And the possibilitys are nearly endless. If you want 100 or more IOs, no problem, they can make up to 9 controlled axes, a mix from analog and step/dir isn't a problem: But the correct installation of the SW isn't a easy task.
The test of backlash is rather easy, you need a dial indicator, adjust the needle to 0, and pull and press the guide of the machine. then you can see how big ist the backlash. I don't think it'll be big,
because afaik the triac have ballscrews.