Our patch modified several of the data files. The *.REZ files are essentially zipped archives. Our patch was created by editing some of the files within the archives and then creating new archives.
I don't have easy access to the modified archive files right now, so I can't tell you the file sizes. I modified the SCRIPTS, DATA, RUDE and ART archives (at least). ART.REZ has that splash screen with 1.3 on it, so it looks like GOG used at least that one.
This is good to know, but I'd like to verify that GOG used all of our files. If so then we can assure folks that that don't need our patch for the GOG version. I'll try to resurrect that hard drive and get back to you on the file sizes.