I did finally try OSS yesterday at YVR. Came off the flight from SEA. Red vest lady directed me to OSS. Told her I wanted to use Nexus so she told me to do so and come back to the OSS lane which I did. Handed my Nexus printout to CBP and went on my way. Only issue was 3 people asked to see my BP. And the somewhat long bus ride to domestic thru and around the airport.