Depends on a lot of things but generally I'd say that its not.
Do you fly CX often? If not, then no.
Do you know if you'll fly a lot next year? If not, then no.
Do you value having some more luggage? If not, then no.
Get the pattern here? Definitely answer the first two realistically. If you mostly fly CX then it makes no sense IMO. If you fly with other OW airlines then I would leave MPC asap anyways...
I'd say CX is about 50% of my flying. The other half with BA. All of it is long haul Y. I chose MPC originally because they status matched me into CX SL where BA wouldn't even give me the time of day and I would have needed to start at the bottom. Having said that I did the math and because of the poor earn rates on CX flights under BAEC I'd still be a bit short of BA Silver so a mileage run would still be necessary. I've found the Asia Miles companion ticket to be great which is why I still continue to stick with the program.