I got the car back today after having the system (and front and rear parking sensors) fitted. First impressions of the new DVD headrests are that they are good but could have been great but for a bit of tweaking.
The headrest poles do come with 12mm adapters which are necessary to fit properly in the seats without wobbling. These adapters have to be dropped into the seat first, and positioned until they click properly otherwise the ratchet function does not work.
The Lexus DVD headrest covers do fit over these wider headrests, but it's a tight stretch.
Picture quality and sound quality are absolutely fine (480 x 234 resolution) with bright, crisp images, reasonable sound from the built in speakers, and clear sound using the FM transmitter built in, playing through the car speakers.
I tested the system with 2 movies : The Fifth Element playing on the front passenger headrest, and Bean - The Ultimate Disaster Movie, playing on the driver's headrest.
Now the bad news:
1. When you play the movie through 1 headrest and view it via the AV in on the second headrest, the volume controls on the 2nd headrest are frozen out. You can get around this by setting it to play out via the FM transmitter on a frequency you are not listening to.
2. When you play a DVD and select a menu option, for example to play the movie, it doesn't choose what you selected. In the case of the Fifth Element, any menu choice would play the movie trailer, but at least after skipping chapters you get to the movie proper. The Fifth Element DVD I used is over 10 years old and maybe the menus don't work in quite the same way. When I tried the same thing in the movie "Bean|", initially the same thing happened, but at least when I pressed the "Title" button during playback of the trailer, it jumped to the proper menu and then correctly to the movie.
Update - after playing with the setup menu on the units, I tried this again, and this time it worked perfectly