Ok, I put my question into action:
1. Called MPC. Found a date near my travel dates that provided upgrade space in all directions. They advised that there was only one seat available around these dates, and that things were very tight, but did provide a combination of dates and flights that would work.
2. Called local CX office and booked the flights that MPC had just advised, and had them put the reservation on hold. They noted that one of the four flights would be in economy, as the equipment that day had no PE. So I ended up with a booking like:
NRT-HKG Economy (B)
HKG-YYZ Premium Economy (R)
YYZ-HKG Premium Economy (R)
HKG-NRT Premium Economy (R)
3. Called MPC back and asked them to upgrade all sectors. They said that since a B class fare was in the mix that they would have to split the tickets out as : HKG-YYZ return, then NRT-HKG, and HKG-NRT separately, and that the upgrade mileage hit would be:
HKG-YYZ-HKG @ 45,000 miles
NRT-HKG @ 17,500 miles
HKG-NRT @ 10,000 miles
I told them that I was very surprised to hear this as I had just confirmed with them (MPC) an hour earlier that I would be able to do this all for 45,000 miles. They accepted no responsibility, and asked what I wanted to do.
4. I told them to upgrade the HKG-YYZ return portion, and the HKG-NRT PE portion, but left the Economy portion as it was, as I felt that 17,500 was not worth it, as in total I would then be hit for 72,500, when I was originally expecting to use 45,000, based on their own words. So currently I am mostly upgraded, except for the NRT-HKG flight, using 55,000 AM miles to upgrade to business.
Q: Am I being a fool for not using another 17,500 AM miles to upgrade the NRT-HKG portion?
Q: I'm a bit miffed at all this, but ready to take it, should I?
Q: Now that I mostly in U class, I will earn Club Sectors and AM miles based on a Business Class earn?
thanks,
RDP
Hard to vouch for your case because it is easy to get R (not B) for NRT (or HND)-HKG-North America. If you can do CX521 or CX549 these are the two flights that normally have PE. 509 might have too but sporadically. If these all happen to not work with your plans (connect to YYZ?) then you'll have to go with what you have now...
Club sectors and AM miles -> you will earn whatever is for B and R that you have now.
I think the cheapest solution if not changing anything would be to just 'suck up' NRT in PE and forget abt the J class upgrade for this sector, heck you might get op up or equipment swap anyway. Then u will just end up paying 45k AM for HKG-YYZ rt. I had a split ORD-HKG//HKG-HND and I hesitated on the 10k upgrade to U for the last segment. In the end I chose not to and I felt it was fine because I was traveling with a companion and the service was so so so so good on that flight in PE anyway. (It's actually my trip report below

)