I can't speak about Global Entry but NEXUS is a godsend. I traveled to YVR weekly and it saved me a 2+ hour wait at immigration just about every time. My flight would always arrive just after half a dozen flights coming in from Asia, and the customs hall would be packed.

Also, at least at YVR, when traveling outbound you can flash your NEXUS card and use the first class line at the security checkpoint. Every so often when I returned home, the US preclearance and security area would be teeming with people on their way back from cruises, and it saved me from having to wait in those ridiculous lines.