I am also experiencing the same transmission problem. I have talked to two service managers in two different dealerships and a Lexus rep, but getting unsatisfortory and conflicting explanations from them. I am getting tired of chasing them for a good answer and giving up.
I also notice a degradation of fuel consumtion since the application of the TSB. I am also getting around 15L/100Km (some time even worse) - not good at all compared to the old RX330. Another thing is that immediately following I took my vehecle for the first service, everything worked perfectly and the transmission was very smooth. However, the good only lasted less than a couple of week. If it is a design issue, how come the transimission would suddenly go smoothly for a few days after something is done to the vehicle and then go back to rough transmission again after???!!!