I have been an avid listener to UA channel 9 for many years and was pleasantly surprised when it was not removed post 11/9. I have developed a huge respect for ATCers everywhere as a result of listening to their efforts, particularly at times of traffic challenges.
I have however also seen the downside (for UA) of this open approach. On one memorable occasion I was at JFK on a 767 flight to London which was delayed departing by an engine problem. As we waited at the gate the engineers were called to lift the cowling and try to fix the problem. The captain was giving soothing words over the PA about how minor the problem was and how soon it would be fixed. Unfortunately for him, "someone" had also, presumably unwittingly, switched Ch9 away from ATC and on to the company channel, so those of us listening were priviledged to hear the exchanges between flight deck and the engineers. These exchanges were telling a very different tale relative to the nature of the problem! As time wore on the poor captain's tortured updates on the PA were getting increasingly baffling to all except those of us receiving the real blow-by-blow account on Ch9.
It took more than two hours to fix and test the problem, by which time I had learned a lot about UA's approach to crisis engineering - which appeared extremely professional, if a little harassed at times!