Was just looking at one-way Business Class fares from Sydney-Shanghai;

If I was to fly on the QF A380 Sydney-Singapore connecting to Shanghai on China Eastern, these flights are $2097 when booked on MU flight numbers. When these flights are booked on QF flight numbers (exact same flights!) the flights are $7043.

Yes that's right, a massive $4946 difference for the privilege of a QF flight number.