UPPDATE: I replaced the Denon AVR-X7200WA with the Pioneer SC-LX901 Elite. ah.. thank god.. much better.
First off the bat, hey-that-is-not-a-console-but-a-mobile-device Nintendo Switch worked fine. That didn't work at all when connected to the Denon. It can still take some time for a handshake, but give it a min or two and the Pioneer will kick in. (the PS4 pro still gives me a little problem.. but having owned a ps4/ps4 pro from launch, i only played 1 game on it.. so no biggie)
Is it the Denon's fault? hrmm.. I don't know. I've never had a TV take so long to handshake as the G6. Maybe the Denon just give up to soon. Every time an input is changed it will always get the no-input-screen-saver. My uninformed gut tells me it is trying to do something with audio.. but that is nothing more than a guess.
I'm but mostly happy now. I don't have to get off the sofa and fight with trying to get stuff work. (sometimes that process could take 10-20min!). So, if you g6 + denon and have handshake issues. Look at getting another AVR.
The mirrored HDMI output is working great too.
changing stuff out is sooo much ez'r than in the past. The process from taking the new receiver out of the box, pulling and reconnecting wires, and setting up the Harmony took like 45min. That, or i do this to frequently. It helps A LOT to label wires
now.. i have this 5 month old AVR-X7200WA just taking up space.. *sigh*.. anyone in NYC wanna buy it "cheap"