I spoke with two Toyota dealers today regarding the fluid issue.
Apparently most if not all dealers have switched to using T4 on ALL vehicles, old and new. The T4 fluid has friction modifiers which should make the shifting "smoother".
According two the different dealers, the T4 fluid IS backwards compatible with Dexron III, however Dexron III is NOT compatible with transmissions requiring T4.
I wasn't comfortable taking the dealers at their word, so I made a service manager call Toyota headquarters and they confirmed that T4 is appropriate for use in Toyota vehicles that originally specified Dexron III. Headquarters also said that if customers are unhappy with the use of T4 they may switch back to Dexron III without running any risk of damage.
I hope that means no permanent damage has been done. My transmission felt like it was slipping which could be due to the excessive wear the on the torque conveter due to the kickdown cable being bad. It could also be that my MAF is dirty or something engine related was causing it.
The shifts are certainly much more firm than they used to be, and frankly I liked the smoother shifts that I had with the T4, but if it shipped with Dexron III, I think I'll continue to use that instead.
Jay.