OK, I misunderstood your above posting. I thought you were referring to those concentric ramped ring headset adjusters that were available for a time with the Easton Beartrap being the most common.

Those expander plugs you linked to do work and work well and are essential for carbon steerers. There are similar models available for steel steerers too (larger in diameter due to the steel steerer's thinner walls) and they also work but aren't as essential since a starnut won't harm a steel steerer.