Hi,
I recently bought a used 07 GS450H here in Ireland. I was quite fortunate as the car was taken for a service before I accepted delivery and the Hybrid battery had failed. As the car was covered under warranty (only 6 months left) they replaced the battery free of charge. The price for one of those batteries over here was €5000! So it seems that they are aware of batteries failing close to the warranty. Have to say that the GS450H is probably the best car I have driven by a long way.