As components to a micron scale engine or 30x bigger/smaller, fine. In the mid 'oughties, the concept of a molecular computer using diamond rods smaller than I describe, was being shot down by vibrations. I wouldn't use diamond much, it is an arms race and fickle factory equipment material. Whatever makes the drive-train can maybe have its vibrations cancelled by lasers. I see banked Ion engines getting a half dozen stars or brown dwarfs. For more space and beyond, antimatter 30 LYs. The rods would have to be wear resistant; they could be switched out every so often. Existing magnetic fields quench easily; they tend to shift around suddenly, we need to know when this will happen and previously have cut power to some of the rods. At maybe .15c, quantum stuff will start to not work well. Our brains still okay, but electricity might be tricky. Some other power source might be needed. Only one high voltage is needed for Eris even, lest the ion engines veer. Here the magnets are moving. When they break, it messes up the ship's power.