jiejie

Both fsf and Ed have good points. I think it comes down to: how flexible are you timewise, in the event of IRROPS? On non-discounted, or somewhat discounted economy tickets, MU should have the ability to put you on another carrier, though you might have to fight like crazy for them to do so. On deep discounted econ tickets, probably the restrictions are written to be placed on alternate MU metal only. As for earning Delta miles, make sure the TA tells you the booking class before you buy, and confirm with Delta (website) that that booking class earns 100% miles, or 50%, or whatever.

With regional segments HKG-PVG and PVG-NRT, there are more choices for coming up with a Plan B than if connecting from a long-haul transpac. With a little time flexibility, in your shoes, I think I'd go for it and save the $300. Visa for HKG is not needed for you, and with a through ticket you should have visa-free intl transit at PVG.

@Ed: Refuse to take "no" for an answer and especially refuse to accept an useable situation 13 hours earlier. If you are heading for Shanghai, MU has several flights to Shanghai every evening. Demand to be put on one of those, or another carrier. If not heading for Shanghai, it would have to be pretty odd place for there to be no other alternatives out on the same evening. If it was on a separate domestic Chinese ticket, you could demand a full refund and then just buy a new ticket from another carrier on arrival into China, though you might pay more. Do what you can from where you are now, but if no satisfaction, be prepared to carry on the fight once you land in China.