I've never seen any of my flight managers upgrade people specifically on the basis they have an IATA card (though I've been asked countless times). I have nothing against travel agents, but if the flight is overbooked, my flight managers have followed the order of HON-->SEN-->*G-->FTL-->*S-->UAGS(no, just kidding, UAGS is with *G)-->Blue. Like mentioned above, the main advantage is discounted tickets. Sorry.