Yeah, I found out about this one a little too late last year. I was 10,000 miles from PE and was getting a seat assignment and mentioned that I was Platinum on AA and the agent said "Oh you should have sent in proof of your status and we would grant you comparable status."

My company prefers for us to use AA for travel but after I sent an email with this info to my coworkers UA ticketing picked up in the office.

Oh well live and learn...