Looking more into it, I appear to have been wrong with what I said originally. I tried the Steam version, and good lord the shadows looked abysmal.
It does appear the GoG version uses the normal retail settings (maybe a few changes but nothing I noticed), so yay ! I think I may have loaded it up after all this time, seen the shadow glitches and immediately thought it had the same issue as the steam version, whereas it has been that way all the time (I previously saw it while playing in 1680x1050, I now play at 1080p and maybe that makes it stick out more). I apologise to GoG for jumping in with this before fully grasping the facts :)
I'm not a fan of the forced v-sync, doesn't the game have its own V-Sync option anyway ? And im not sure if this is causing a strange frame skipping/stutteryness when around camp fires, because on any other version I can run around these without issue, but on the GoG version I get the horribleness.
Did I read correctly that GoG staff can send the original files that remove the V-Sync lock ?