One problem related to radiator hose has been reported for the 2006 Lexus Rx400h. The most recently reported issues are listed below.
No failure, yet. But vehicle (Lexus Rx400h - 2006) is a hybrid. There is a separate cooling system for the hybrid components (inverter, and electric motors in transaxle). Coolant is leaking from the transaxle. If all coolant leaks out, the inverter will fail. Without the inverter, there is no power - no electric steering, no electric brakes, and no motive power to the wheels. Additionally, the coolant may leak somewhere or onto something that may short out or cause a fire. This is not a leak from a worn out coolant hose, but directly from the transaxle. Being a hybrid, the availability of electric power is absolutely essential. There have been reports of inverters failing (just check the Lexus. Toyota and other hybrid forums) on the highway at speed, leading to a complete loss of power. To the best of my knowledge, there have been no injuries or accidents, but the potential is frightening.