Looks pretty good in the XY direction, I was curious as to what kind of speeds a MPCNC can print at. It has so much torque and rigidity since it’s meant mostly as a CNC but a ton of moving mass compared to most dedicated printers, moving motors on all axis. I wonder if you could mount the motors on modified corner blocks like a H-bot or CoreXY without compromising the CNC aspect of the machine.
Pretty nasty Z-ribbing though, possibly due to the US standard screw on the Z-axis? I know that can cause problems with printers. Though Vicious gets nice prints out of his, so it must be solvable. Maybe you need to set layer heights in US increments?