AA status doesn't help during the transfer, the FastTrack at the FCC security is paid for by BA and available only if you hold a BA F or J boarding pass. But the lines are so long now that you have to fight through the crowd to get to the FastTrack line (which is quite fast, btw). I've done inter-terminal transits at LHR during September 06 in 40 minutes (at 6 am) and in 2 hours (later in the day). So the time and crowds really matter and change the time required drastically. I've heard of people taking 3 hours for the connection now (often landside is faster if you have FastTrack access, when the FCC gets this backed up; but again it is not predictable). The excessive crowding during peak times makes for an incredibly bad experience.