I was skeptical about them, but they really do hold on to the pins. I put some in the border of the quilt I just started quilting, to see how well they stay on through the quilting process.
The only ear plugs I can think of are the soft, squishy foam thingies that they give you on the flight line or at the range. I tried a pair and they don't hold the pins at all - they pull right off and you might as well baste with straight pins, alone.
But, the Pinmoors stay put. I picked my quilt up off of the table a couple of feet by a Pinmoor.