This past month, I was talking with people online who were thinking of using DH for playing Pirates of Dark Water (with the serial numbers filed off). The core resolution system itself was not the problem. In fact, it was agreed that it would work well: e.g., GM spends Fear for Dark Water to show up. However, the project didn't really go anywhere after it was pointed out how much work it would require to create new classes and domains for Daggerheart that were actually thematically and tonally appropriate for the setting.