I doubt the 1K agent, who are now not dedicated 1K agents but seem to be just the next agent that answers the phone, knows much about the change to the Mileage Plus program. Historically, training has left a lot to be desired.

United Insider has posted that anything other than a date change will likely be priced at the new rates.

A date change is a ticket revalidation--not a reissuance. What you are thinking of doing requires a ticket reissuance and is not an involuntary change due to scheduling.

Looking at it from that perspective, based on the information we have been given thus far from someone at UA who is likely to know far more than a 1K agent, it appears pretty clear you will be reassessed at the new mileage levels if you move up in cabins on a partner award.

I would like to be wrong on this as I have a partner award with the same issue (BKK to ICN in Y on TG connecting to JFK on OZ in F) but, with this customer adverse United, I doubt I am.