An anecdote:

About two years ago I was flying GIG-ATL-MAD with a big stopover. GEtting my bag in Atlanta I say that they had totally destroyed the handle mechanism of my bag (a mid priced large upright wheeled type thing). I went to baggage services to report it and the woman started to say, "Handles, wheels and projecting parts are not covered......." at which she paused and said, "oh, you're PM, of course we'll take care of you".

They then produced a replacement bag which unfortunately was too small. She then asked me to wait awhile and came back with a very nice bag which was probably worth twice what mine was worth.

I strongly doubt that any of this would have occurred if I were not PM. (and yeah I did write in to DL complimenting this agent).