I have no doubt that Toyota is working to solve the issues with the U660E 6 speed automatic transaxle.
Another TSB related to this transaxle issue, came out on 5/17/07.
It's TSB TC007-07, and calls for a re-flash of the TCU.
I'm going to my dealer tomorrow 5/29, to have it done.
I've had the once after each engine start 3rd-4th shift slip (flare) since about 1200 miles.
Afterwhich the transaxle works normally until the next engine start.
Here's a link to actual video of my car doing this with about 5700 miles on the car:
(it's helpful to also have your sound turned up to hear the engine)
http://www.ori.net/edporch/U660Eflare1.wmv
I haven't pushed for the transaxle replacement up to now, because I'm still not convinced that Toyota has a fix that can routinely solve this, with a LOW RATE of failure. (like normally is the case with auto repair)
With all due respect to BoloMK33, I have no doubt that his car's transaxle issues were fixed.
But all one has to do is read the toyotanation and club lexus ES350 forums, to see an abnormally high rate of cases where when followed through from beginning to end, a replacement transaxle did not fix the problem longterm.
In some cases, the transaxle would slip (flare) when driving away from the dealer after a transaxle replacement!
That said, I've always had a gut feeling that the issue with this transaxle is at least in part a firmware problem too.
TSB TC007-07 has finally gotten me to get my feet wet with solving this issue.
I'll begin by having my TCU re-flashed.
If that doesn't fix the problem, I'll follow through with the transaxle replacement.
I'll report the progress of my case starting with the "flare" problem I've outlined in my above video so that my case can be documented for other people to see here, and on the toyotanation and Club Lexus ES350 forums.