I was spotting yesterday at the beach when i saw BA16 taxying down Twy C and turn left onto B10 for a departure on 16L. They were doing Simultaneous Opposite Direction Parallel Rwy ops at the time with departures off 16L and Arrivals 34L, it was quite an awesome sight to see the 777 climbout of 16L. From a fuel and time perspective i thought it would have been better and not wasted as much fuel to just depart on 34L because after it departed on 16L it did the usual sharp left turn east and then turned right to do a wide loop of Sydney to head Northwest.
http://www.jetphotos.net/viewqueued_b.php?id=2434986
theres a picture of a Qantas 737 with the BA777 in the background holding short of 16L.
Speedbird 16 Climning out