Personally I don't know why they bothered with the paddles anyway. When you move it into sequential mode, the difference between each 'gear' is noticeable, significantly so if you knock it down a couple. The paddles on the other hand, utterly useless.
I'm in ECO mode all the time as I particularly like how smooth it is and how it restrains my monumentally heavy right foot - the savings I've made going from an IS250 manual to a GS300h auto have been drastic, and that is in part due to ECO mode moderating my driving.
Unlike my friends BMW which also has different driving modes, it's refreshing to see the Lexus modes actually translate to real world performance - ECO to normal is a bit more pep in it's step and ECO/Normal to Sport is drastic.