Ok well, 3 phase will actually be better for a photo rig because often 3ph motor as a lower step angle, often 1.2 deg rather than 1.8Deg of a standard stepper so give a smoother action, but this will depend on the motor. Thou in any case 3ph is smoother and are stronger motors in general because of the extra phases so will always be better than 2ph stepper in this environment as you can crank up the micro-stepping on the drives which helps to smooth the action of the motors.

But to be honest I'm wondering why your going with a stepper system, and a cheap one at that, on such a high-end motion control rig.?
DC or AC servo will be much much smoother and the motion controller is capable of 500Khz so will easily handle higher resolution encoders which is what gives you the smoothness and resolution.
Obviously they are more expensive but I would have thought a price worth paying if you are prepared to go high-end on the controller, It's a little like having a Ferrari engine and fitting skinny little tyres with weedy brakes.!!