From all your advices here and some web searching, I think it is safe to believe that 6WA=full black panel display=instrument panel w/ extended functionality.
Btw, this option seems to cost just GBP 125 (pre tax) in the UK, or comes free when you order Pro Nav. Dealer here told me it will set me back HKD 4 thousand something (did not give me the exact figure). But don't think I have a choice as it really makes a big difference. It would be a much nicer customer experience if we have a detail option list when ordering the car!