Kernowlexus, I've just done exactly the same thing! Had an RX300 SEL for 8 years (of it's 12 year life) and it's done 139,000 - never broken down, always reliable, comfortable, etc. Was unhappy with the fuel consumption though so started looking round at other 4x4s - Kuga, RAV4, CRV, Quashquai, Tiguan. Whilst they would all have been more economical than the RX400h I have just bought, I was soooooo disappointed with the lack of refinement and spec. All the stuff in the Lexus you take for granted, and it's a sorry situation to be test driving cars without all those little touches. Hence why I eventually (after 18 months of looking at different car models, and driving my husband bonkers in the process) went back to a Lexus.
Good luck. The RX300 is a fine car.