First, think about your chemistry and how you react to other metals. Have you had issues with costume jewelry turning your skin green shortly after putting a piece on? Does the plating on other pieces come off quickly for you (whether that's rhodium or YG over sterling or others)? I have skin that turns green if it comes within 12 inches of costume jewelry, and the plating on rings comes off in record time for me. Even bracelets and necklaces are an issue for me if they receive a lot of wear. If you are the same kind of person, I would say it isn't worth it
However, if you don't have the same kind of issues then it is certainly worth a shot. Plating on necklaces commonly wears much more slowly than rings, especially if it is not a piece that is worn daily or left on constantly. Depending on the quality of the plating, it ought to last longer than the plating on a ring, and when it fades you can certainly replate, as it isn't terribly expensive to do.