Ok, if I understand right, speed in Accelstepper lib is actually stepping. So with my driver set to 1/2 step and with motor 1.8deg per step, speed of 400 gives some result. With gearbox on, motor starts to spin now, not just click. But still, most of steps are missing.
Ok, it works with speed of 400. Tried another example with prop. control. and it doesn't work (well, with gearbox on motor). Problem is in stepper.runSpeedToPosition() func. Motor just clicks with it. And continiously rotates with stepper.runSpeed();