Depend on your flying pattern, the most important benefit is Seat Guarantee which guarantee a seat for you 72 hours out, which is critical for PVG / PEK commuter route. Since I get Gold I have been paying V-subclass fare to fly into Shanghai Hongqiao, the convenience is unbeatable and that flight is routinely sold out in Y or J and you cannot get anything less than K-subclass if without the guarantee.

And with Gold you have higher OP-UP rate than SL (I got 2/40 when I was MPC SL due to 5 year anniversary / Xmas peak season, 2 / 16 when I was MPC GO on sold out flight - which I use seat guarantee to get seats)

It's also the convenience when packing that I used to be comfortably fly with 20KG luggage limit but with MPC Gold I just don't bother and throw everything in now