Since nobody has answered about IRROPS:

My experience with IB on the ground is abysmal. Typically, customer service is not a concept they grasp, other than one baggage desk woman at BCN, who is positively brilliant, Er, probably was, as I can;t imagine they can tolerate that for long.

One LAX-MAD flight in Business Plus, a minor discrepancy in Lady JDiver's ticket (we were allowed to fly out of SFO on AA with it, IB had assured me it would not be a problem, and we once again had no problems with AA on the return, nor with IB at FCO nor MAD).

The upshot is they could not deal with it (didn't want to deal with it) for the hours the check-in TBIT desk was open, and their final offers (supervisor) was I could fly, Lady JDiver could not. On our 45th anniversary, that would have been brilliant (and likely not conducive to a 46th). It actually took my calling AA, who contacted their liaison to IB, who called LA and told them "let my people go" or the like. We made the flight with less than a half hour to spare. (I do speak Castilian Spanish fluently - language was not the issue.)

This has been the same with Iberia for the decades I have flown them.

BA - I have had several issues with BA over time, where basically the translation of the poor English and/or inability to hear my questions (or to reply noncommittally that basically, what had happened was beyond their ken and purview) was basically "pound sand, sorry".

AA - I have had a couple of incidents over the years, one in which I called the EXP desk and was told not to worry, I was protected on the next flight and all I had to do was, now that I called, proceed to the DFW Admirals Club at my leisure to recover the boarding passes associated with our new flight. At the Club, I was told nothing had been done, and was disbelieved about calling until I was able to show the number and time on my cellular. I did not get out on the desired flight, nor any time that day (by that time, all seats were gone).

But in the muchness, I have found AA to be more responsive, particularly if I had done my homework and called them with alternative flights, etc. (Yes, I saved them the time and effort and made it easier for them to do their job; that works for me.) So I have a pretty high percentage of AA doing things right, but not to perfection.