Thanks for sharing. I was not aware of this. I recently got my hands on a 1stgen Eclipse.
Its says in the guide that you should use the HDMIs in the TV it self rather than the ones in the Soundcenter if you want to benefit from Dolby Vision. I will do some tests and report back, since I have the latest ATV available.
However, if you use the HDMIs in the TV it self I do not think you can use the PUC cable, hence you need to use the AppleTV remote.