Originally Posted by
FlyerBeek
Yes, but if any upgrades clear prior to going to airport control the OP will be at a disadvantage (within his status group) since he lost his upgrade request timestamp when he was confirmed on the 7:45pm flight prior to switching back to the 6:25pm flight.
-FlyerBeek
A major difference is whether a new PNR is issued or if the same PNR is kept but with new flights. Seems like an upgrade request timestamps will be kept with the record and not just with individual flights.
If it is with the record, it won't be so bad to change flights.