Dan- thanks for the MS reference to my post! Glad you think its helpful. (Thanks ckmk47 too for the feedback)
I have a Sienna XLE with Plus package and 8 seats. Has almost all the features of the Limited trim as far as I know (except no HUD and seats are only heated not ventilated).
Power is not an issue. On normal driving mode the acceleration is diminished to improve efficiency, but in Sport mode it has more power than other minivans (though it will affect your MPG)
The lane assist is good for self driving. Not great and certainly not close to Tesla. If you hang a water bottle on the steering wheel it can self drive fairly well but the driver has to pay close attention. It loses control taking curves in the road (at 65mph it handles most normal curves, but at higher speeds it has a much lower success rate).