I wish we had some real data/ numbers.....everyone says it is the best but from my limited perspective it struggles to carry any payload past 13 hours.....If I see more than 150 passengers on ULR flight I avoid it as a staff traveler because you will be offloaded! But then again I don't know what type of cargo loads they are carrying.
But in fairness every plane in the world will have start to have payload restrictions when max fuel required( except 77LR)