The one issue I just thought of is with communication. Would you have to stop to make a transmission? If so, look at the time it would take for earth to receive the message, and time to get a reply.
Unless there is some sort of connected "subspace" theory that can be utilized. I can see a ship being nearly cutoff during most of the mission.
Oh that's simple, you fire a torpedo with its own warp drive back to Earth with a recorded message, it then drops out of warp into Earth orbit and broadcasts the recorded message in the em spectrum, so there is no real need for "subspace radio".