Is GOG version properly supported compared to steam version? Just found out recently that some of the games on GOG either late with the patches or not supported by devs at all.

I'm not sure if GOG has the beta patch, but it certainly has the last stable patch that added hardcore mode. The game wasn't really patched that often after the release to my knowledge. We'll realy only see once the DLC is out, but for now I don't think it's one of those games that aren't patched.