I used Nexus and GE at an airport for the first time in two years this past week at YVR. Iris scan worked but the questions took forever to be accepted (easily 10 seconds). Not sure why it was so slow as no one else was using the machines.
I did head up to the enrollment centre and asked and asked about updating my (basic) DL. They said that they don't need that anymore.
My DL expired in April and I've used Nexus headed down to the U.S. by land w/o issue.