Just playing around with HKG-MEL flights and it now gives me the option of MH from Kuala Lumpur (CX from HKG-KUL first). Only adds £29 in taxes over the direct CX J HKG-MEL but does add 70k Avios for a redemption.

40K Avios + £114 tax for J for KUL-MEL.
120k Avios + £129 tax for CX J HKG-KUL, MH J KUL-MEL
50k Avios + £100 CX J HKG-MEL

Taxes don't seem too bad there. Maybe long haul is better tax wise?