I only got my RX a few weeks ago after running an IS since last August. If the VED is an issue then either go for an RX300 (but watch out for 23/03/06 on ones, they're £555 per year too) or a 400h. Here I'm assuming the RX450h is too pricey.
RX300 is a traditional V6 with a regular auto. RX400h is a V6 with CVT and obviously a hybrid. I was told the RX300 could be a little sluggish and thirsty but the RX400h went like stink for a bus and the hybrid system took the edge off the poor fuel economy. I wouldn't have minded either because I don't regularly lap the Nurburgring and how a car makes me feel is more important to me than how often I have to stop at a petrol station. As it turned out I could stretch to a low mileage 400h and I couldn't find a bad thing to be said about the hybrid system's reliability. As was pointed out to me when I asked, if it's got air suspension it will have up and down buttons in between the heated seat controls and the ciggy lighter. No buttons, no air suspension.
I never gave a thought to the CVT because I've driven plenty of CVTs and know there's nothing wrong with them. Lexus, Toyota and Subaru really would be struggling if everyone believed what a motoring journalist thought after spending an extremely thorough 15 minutes with a car. And unfortunately the internet being the internet this nonsense is repeated as fact on every car forum out there. Ever driven an Outback with the 2.5i and Lineartronic CVT? It's a lovely thing.
I'm no expert on Lexus. I've been here less than a year. I'm sure someone else will chip in if I've got any of that wrong.