Getting ready for an Alpine tour and really confused about the baggage regulations from airline to airline. We are flying out of USA on AA to Dusseldorf and then flying Air Berlin to Salzburg. I had planned to travel with a carry-on roller board and a backpack. The backpack would be smaller than the roller board but bigger than a laptop case or a purse. This is how I travel domestic all the time if I don't want to check a bag. AA allows two carry-ons but Air Berlin is more restrictive and will only allow a carry on and a personal item (something small like a purse). My question is since I have one checked bag free anyway would it be better just to check the roller board just in case there is a problem with having two carry-ons when I change over to Air Berlin. Coming home I don't think is an issue because we are flying British Air and their carry-on allowance is even more liberal than AA.
Thanks