I am using LinuxCNC, which is intimidating from the outside, but really quite easy to set up, and incredibly powerful. It’s also free. I looked at mach 3/4 but the cost for the software is significant (Mach 4 costs almost what you spent on your whole upgrade)
Would you say there is a noticable difference in the way the shapeoko cuts or runs since your upgrade? or is it fairly similar? I haven’t had any issues with mine, It definitely runs a bit smoother than the carbide board- I can still hook my Carbide Board up to compare, but don’t use it full time due to reliability/disconnects.