I wonder what their catering service is like in LHR. I've never had anything but good service on AV, but I've never flown them long haul.
The equipment change stinks, but such is life. You're paying for the destination/route not the aircraft. Plus the A330 business seats aren't awful or anything. If you're a fan of IB/AA/BA, you SHOULD give them your business rather than chase a possibility with someone else. If you like AV and just hoped that it would stay 787, then ok, you got burned a bit, but bad service is bad service and can happen on any airline.