I would argue that changing dark epic's soul drain to the longer cd version is a less jarring change than making it into spirit drain. I don't think I'm going too far out on a limb to guess that an overwhelming majority of players who take dark epic, do so to reach the current version of soul drain. And those that take soul epic do so for power boost, and only some take soul drain, just because it's there and they can fit it in their builds. I contend that changing dark's soul drain to the 240s cd but retaining its ability to use PBAoE sets would be far less jarring and much preferred over spirit drain. Spirit drain, while having the familiar 120s cd, would require changing sets and would still make players adjust to a much lower uptime in the buff. Soul users, many of whom probably don't even take that version of soul drain, would have the option of using spirit drain if they so choose but would more than likely be entirely unaffected by the change.