Do not mix ERAS and any GOF program/resource mods because they are usually incompatible.
Efforts are made to keep any ERAS updates compatible with previous saves. I can't guarantee any future changes will always work with older saves, but effort is made to keep old saves working and of the hundreds of changes made, saves from 2017 ERAS saves are still compatible with the new version of ERAS; they still load properly.
I also don't consider GOF 2.0 and 2.5 an upgrade to GOF 1.2 or ERAS, because GOF 2.0 actually removed much of the script improvements, characters and ships from GOF 1.2. I'm not really sure why it was considered an upgrade to GOF 1 because it is a lesser version. Also, ERAS attempts to be more historically accurate for the time period, so ships like the Surprise are not part of ERAS because it is a ship design from the later Napoleonic period. However, ERAS did add many more characters and other ship types, far beyond what is available in GOF 1 or GOF 2. I also still contains all the script additions from GOF 1 that were removed in GOF 2 and also contains many other features added that were not available in any GOF version.