Driving the avalon/Camry 2gr fks vs the new ES, it seems the Lexus is tuned more aggressively, or so I have heard.
I think that thought originated from a savagegeese review (I love him, btw) that was wrong. ES/Camry V6/Avalon V6 have the same exact gear ratios and transmission tuning. ES with smaller wheels and softer rubber can
feel faster than the same engine/transmission/car with larger wheels and stickier rubber (Camry XSE V6).
It will be very interesting to see how an IS 500 is executed because while we are all postulating and guessing, turbo motors should in theory make it somewhat easier for Toyota to change the tune and feel of a powertrain for power-specific applications like a sporty IS 500 vs. a luxurious LS 500. Toyota has historically setup most of it's powertrains for maximum reliability and minimum fuel consumption, and then standardized that format across the vehicles that use the powertrain - just like Camry, Avalon and ES, or Highlander/RX.
V35A-FTS could feel and behave very differently in a much lighter, sportier IS - and it should - or they could say, "we know this tune works, we put a lot of time into it, so we'll just use it across the board: IS 500, LS 500, LX 500, etc."