Yep the 430 is more luxurious inside, but the 400 for me is luxurious enough, feels like it has more space than 430.
Also agree that Jags are undervalued, but not as much as the LS, and though Jag build quality improved still not IMHO up there with the LS, and the engine bays of Jags seem like a real nightmare to work on.
seems like the chaps at Lexus focused on the ease of maintenance (as much as one can with a 4 litre block under the bonnet) not just making a good runner in the first place.
As to the wallow, it takes a while to get used to, but when chucking around corners it seems that only M series BMW's keep up, or maybe M series drivers just know the limits of their road-holding better than your average driver!
Not been in a 460, so maybe even more luxury than the 400, but until my 400 dies, do not see any reason to trade up/across.
I guess like the original Morris Minor or VW camper, I think the 400 will be THE classic because it is the first of what was a new breed of engineering and design coming together. (I still remember my Grandads split screen Morris Minor with affection - and nothing else later in the Minor range ever appealed)