Does the GOG version have the patch 8
? It seems that the developer posts no changelogs to GOG, according to the pinned community topic
patch 7 is the latest.
The GOG installer version appears to be setup_red_faction_guerrilla_re-mars-tered_cs4931_(23846)
GOG's is labelled Patch #7, but all the fixes listed are the same as Steam's Patch #8 except for Steam-specific stuff like achievements fixes.