Particles come to my mind first when it comes to dust, as it's not really a fluid, but a bunch of particles

I don't think there's a right or wrong way to do it, I was simply wondering why you chose to use fluids.

With your test, it seems that when the balls hit, there is a realistic amount of dust thrown up; however when they roll, a huge amount is emitted. I think if you had a dirt floor, which is where the dust would be coming from, it would stop them from rolling as it has much more resistance to movement than a frictionless plane like you have now. By stopping them from moving with the dirt, you would also remove the extra emissions.

That's my only critique from what I can see. Nice job.