I really like my Mk4 LS400 a lot and I plan on holding on to it, but there are things about a 430 which I like better. For instance, the cabin of a 430 is far nicer than that in the 400 in my opinion.. It's a definite improvement. There's not enough wood on the dash in the 400 for me, ---it's a bit swathed in plastic, even though it's high grade stuff. On the negative side, I think there is potentially more to worry about when owning a 430 because It's technically more advanced, which can bring its own problems. The gearbox failures, for example, though extremely rare, (due to water/atf mixing) is still a concern on the 430, but, in fairness,with meticulous servicing this should never happen. Air suspension failure would prove very expensive too, but how often do you hear of this happening? I would definitely consider a 430/460 in the (very) distant future to replace my brilliant 400 but the 600 would be a step too far for me I'm afraid. Even if prices tumble, I wouldn't buy one. Replacement parts will be exhorbitant, even for Lexus, you just watch.