Thanks to everyone for their advice. Happy to say, all went very smooth last Sunday from BRU to DFW via LHR. I did get New First, which I have to say was brilliant (I loved the cabin decor, and the 747 is still my favorite aircraft). Service was outstanding, but didnt have that Chocolate Dessert that VK mentions often, so hopefully on another menu cycle I will be able to try it. The transfer from BA International to AA domestic at DFW was pleasant enough, and quite easy. My AA connection to JAX was delayed slightly, I was able to use the Admirals Club Lounge! So all in all, painless. Now for next Sunday JAX to MIA, connecting onto BA CW back home.
