Adding to the discussion stepper vs dc motor:
Of course with stepper you have worst EMI noise, but through commutation you also have the issue with dc motors. I find the key difference is that dc motor forces you to have a closed loop, while when sticking with steppers you can do both. I think there is some potential we can still use with dc motors (1/16 step mode) which should bring improvements in speed, ringing effect and torque.
I am really curious about your results of dc motors vs steppers, looking forward to that!