Hi Steve - As a general statement here goes. 1) The more steps the smoother the motor operates but depending on some factors it may not reach high speeds Some drivers have better response then others to mid range vibrations and high speed back voltage issues 2) You have a 1.8deg per step motor with probably 5% tolerance. This means it's not much point going past 4000 microsteps as this is about the same as the mechanical accuracy. 3) so depending on your application positioning or movement you pick the microsteps to suit. If its a router for instance not much use going past the 4000 microsteps. So 5% tolerance is =1.8*0.05 = +/-0.09degs. 4000 microsteps =360/4000=0.09degs so if you picked 8000 usteps you would have a theoretical step of 0.045degs but the motor could only achieve 0.09deg so no point in using over 4000 usteps for positioning purposes. But if its for smoothness say a camera dolly then use as many as you need to get the smoothness you want. Oh and drive at the highest voltage possible always better for steppers but only set the current at what you need to stop overheating or set at correct current.....Cheers Peter S