I've done this "pit" multiple times...never had an issue with or without bags. It's much faster than showing up at the regular US checkin, whenever I've gone through the little connection line is like max 50 people and the regular USA checked in people is easily 200. I breeze through even without NEXUS. The only trouble I've had was last time a US agent just decided to pull me in for extra questioning as I was about to leave the hall.