Another data point on 2.5K miles "surcharge" on exchanging award ticket.
I have a SFO-Syd RT ticket of XN (80K miles) upgraded to PN with 80 MileagePlus Points.
7 days before the trip: I changed the outbound flight from SFO-SYD to SFO-MEL; GS representative changed in 2 min. expert knowledge and efficient.
5 days before returning trip: I called in to change the returning flight to the same flight on a day early, website showing XN and PN available. This time, GS help line asked to pull additional 2.5K award miles per ticket, citing that the current system uses dynamic pricing and there is no longer "saver award".
I felt that United has provided great GS benefit already, so I did not hang up and dial again for the extra 2.5K/ticket. But the experience really highlighted new inconsistency in implementing policy when it comes to award ticket changes.