I think you can trade your dongle for a serial now.
Agreed. I had a Nucleus unit that was faulty out of the box. Returned, and borrowed the store's own demo unit for a shoot last weekend.
The system is really nice, but it is entirely unreliable. You have issues getting too close to the camera with the FIZ, sometimes the FIZ would lose the motors, only to find them again (and jump to the new position). This seemed to happen in blind spots all around the unit.
Fortunately the shop allowed me to return mine.