The G540 is a decent box but in the CNC plasma realm it really needs to be used in a way that doesnt allow the drives to take a grounding. The G540 is prone to noise issues as well. We have a G540 working on a Thermal dynamics hi frequency unit since 2011 and one on a Maxpro 200 since 2013. Properly shielded from the EMI they will last but that is something rarely done in the industry. The G540 is almost what I would call hobby grade but anything in any configuration made to work in production should not always be called hobby grade. The build is looking interesting. One thing you may notice from direct drive is a fast rapid but a massive torque loss at higher acceleration rates and those rates used by folks running a reduction. A 20 pitch gear with a .750 pitch diameter or even a .625 diameter is much smoother than a 14.5 degree pitch gear and rack so your definately on point there