Thanks for the replies, Lexus told me that the IS300 used those types of leather but maybe I or they misunderstood and the higher spec is only on the RX, LS, etc. as suggested by Colin.
However, I am certain that the leather in my Premier was much softer and nicer than the F-Sport Takumi, I also tried the rear seats which I think would be identical in both cars (F-Sport front seats are "sports seats" of course with different design which might make a difference in comfort, feel, etc.)