I like the scenea ambilight effect with turned off TV. But instead of turning it off, it just switches to HDMI1 when my Mythtv box is running.
I found out, that the ambilight button of my old 7603 works with my 7605 what solves the problem (for me). So I can also switch on ambilight without zapping through menus first. I mapped the key to my Harmony remote.