Hi Adrian, congratulations on your recent purchase. I recently bought a set of wheels from another member but couldn't quite decide on whether I liked them enough to keep them. What really helped me to come to a decision was the change in the ride that I couldn't get used to. With lower profile tyres the ride was just a bit too hard, and an LS400 isn't built to have a hard ride. Anyway, I had the originals refurbed and it was like getting an old friend back! Hope you make the right choice, but for me, if I changed the wheels again I'd get the same size as the originals with the same tyres.
Phil