Yes, there are tons of reports when flying through preclearance (YVR, YYZ mainly) - but only for US citizens, LPRs, and Mexican nationals who remember to pack their GE cards. Not much success for all those other GE members who don't get the card. (I've asked CATSA about this, and they won't budge.)

It's interesting that this page has changed yet again: in the past it used to mention Nexus lanes domestically (for Nexus members only), and Nexus lanes for preclearance (including GE, military, etc). They then revised "Nexus preclearance" to "Trusted traveller lanes", but still had a "Nexus lanes" (domestic) section. That "Nexus lane" section is now gone, so it seems like they now might be opening expedited screening to all their "trusted travellers" (of correct nationality) consistently across Canada.