You cannot compare SoD with Live, Live-copy emu servers, or any other custom server.
Other than the zones, and the art, 95% of everything else including formulae, mobs, drops, lore, quests, scripts, and features are in house created by the developers.
As far as "how much" content is currently in game I'm not sure. There is a considerable amount that will take you a good long time to experience and most of the Planes and Lost Dungeons haven't been worked into the story yet.