Ian, welcome to the forum . there's lots of thoughts here about the Ls430 and the Ls460 and differences etc
IMHO you're nuts to even think about changing your tiny mileage briiliantly looked after ( I'm assuming ) Ls430
She'll last another 100k miles minimum....... BUT no doubt the Ls460 is a fine fine car and you'd be well pleased with the change, apart from maybe the bills that might come with it .... lap of the gods stuff that
You have a very fine low mileage Ls430 so I'd say " stick with it " . if you want
Good luck with your decision making
From a long time Ls400 owner and fan and can't see the point in changing cars for the sake of it guy !
Malc