It is quite unused - I breezed through last Sunday, never seeing anyone in line from the top of the escalator until I was on the train. I don't recall ever having a wait, and only a person or two ahead or behind me.

Having said that, my returns from LGA and DFW were equally empty. In fact, the only place I ever remember not walking directly to the front was at LAS, and that was behind one couple that was just wrapping up.

Don't spread the word - you'll ruin it.

(the PIT normal and preferred lines are always packed - at least when I'm there)