I used ArdsimX. A X-Plane plugin to drive steppers directly connected via Arduino-Boards. This plugin was also able to use the Propwash-Board. So you only need 1/4 of the pins on the Arduino.I have never had any issue with #smooth movement# at all - what do you normally use ? it will be the software, not the stepper or driver that is causing an issue.
ArdsimX became SimVim and the movement of the stepper needles was super smooth. But as mentioned you could only use one Arduino Uno for I/O. That is enough for the Steppers in a 737NG or A320, but not a GA airplane with steam gauges.
So I did never use this in my simulator. I did support this development for some years but could never use it. Today it is named Realsimcontrol.