Tomorrow I will do another drive cycle and check the codes and I/M status, but NOT reset the CEL. Then I will check the I/M status again when I get home. If they remain "READY", I will just try doing a few more dedicated drive cycles to see if I can clear this code. In the meantime, I will continue to use my trusty analog "CEL eliminator" (aka piece of construction paper.)

There are some interesting videos on YouTube showing how they can test an EGR valve operation against a set of technical parameters. I don't really want to pay a technician 80/hr if I can clear it by driving. But, if push comes to shove I may have to bite the bullet.