Just for reference, these ex-AMS fares usually have a EUR 300 change fee.
The more substantial issue than the change fee that affects most people in this kind of situation would be the advance booking requirement, i.e. cheap "ex-EU" are often INCEUxx, xx being the number of days in advance that it needs to be ticketed, plus the fare bucket availability.
Unless the traveller can postpone the trip by the number of days in xx onto the date when the I class is available, the fare difference can be quite large depending on what can be booked at the time.