So far my new Global Entry card has been used a few times.

MCO had never seen one but after normal inspection was accepted.

PHX had never seen one before, but no problem.

DAB had never seen one, was shown to the most senior person working the check point, and was then asked if I had another ID. Ended up showing them my passport.

LIT had never seen one, was shown to the most senior person working the check point who after a short discussion decided it was OK, said they would look for updated materials to train the staff.

MCO no problem.

SEA had never seen one, gave it a long look, asked another TDC about it who said there had been a sign off memo on it recently telling them it was OK. Decided it was OK but also asked me who I worked for at the end of the conversation. Not sure if that was related to GE card or just a SPOT.