Hi men8ifr,
Our KMotionCNC software and KFLOP can do closed loop to Step/Dir drives and typically works well because the motors can be moved in a controlled manner even when the glass scales are not providing information due to system compliance/backlash/stiction/etc. But overall performance will depend on your mechanics. See here for more info.
KFLOP by itself can support this but only has single ended encoder inputs. See here for more info.