Just to clarify - Nexus works great with GE machines.

Scan your card face (picture) up and push it to the top right corner of the scanner.

In 5 years of Nexus, in transborder air travel I've been required to produce my passport once, but asked if I have my passport "on my person" probably a dozen times.

For boarding flights in the U.S., I have had a few occasions where the GA was not familiar with Nexus. Usually a brief argument ensues and I have the choice of either producing my passport or waiting for a supervisor to "educate" the GA.

In all instances, I've simply produced my passport.

I wouldn't recommend travelling trans-border without a passport. In 99.9% of occasions you will be ok, but the consequences of being called out can range from nothing to quite severe and are somewhat up to the discretion of the Agent.