Interesting mod. Personally I prefer Gold just because it's the official polished version of the game, but I do agree with the other posters who prefer Craymen in The Lost City. It doesn't feel quite so lost when a bunch of mages found it before you did, and I thought that the Craymen were sadly underused. They're brilliantly creepy enemies and perfect for The Lost City, but having said that, sacrificing Song of the Caverns, The Mage Towers, and that brilliant bit in The Downwind Thieves Guild where the trip-hop kicks in as you creep into the bar, is just not worth it.
One thing I'm curious about is whether the levels added to Gold were cut from Dark Project due to time constraints, or whether they really were just bonus levels made for the re-release. They don't feel out of place at all to me, which is one of the common complaints I'm seeing on that Eidos Forums thread linked to a few posts ago.