See, so was I - and it was fine BUT the TV remembers settings for each input, so my Xbox would automatically have game mode and a few other changes I did enabled, each time I switch to it. When I was using my receiver, It was in effect only one input in the TV, so I'd have to manually do this every time.
The TV remembers all your picture settings for Game Mode separately than Movie mode, so I basically have two sets of settings I toggle between. All my game systems share the same Game Mode settings which work fine. And yes, I have to turn Game Mode on and off depending on whether I'm playing a game or not. But I don't see that as a big deal. Let's assume everything's already turned on:
1) Select proper input on receiver
2) Switch game mode on or off (if necessary) on TV
That's pretty much it. If you use the TV to watch Netflix or something, then just select the "TV" input on the receiver which has the optical cable run to it and you have sound. That optical out always works with no shenanigans. There is no difference in audio quality between optical and ARC.
On the other hand, if you run your PC or game system to the TV first, and then out through ARC or optical, you are potentially sacrificing sound quality because ARC/Optical only supports 5.1 audio.
I don't have any kind of HDMI-CEC or auto-switching turned on because in my experience it sometimes switches when I don't want it to, or ARC simply stops working properly. Sometimes I want to start a firmware update on my PS4, then watch/play something else, and not have the TV automatically switch back over to it when it's done, right when I'm trying to kill the boss on the other game. That kind of stuff irks me, so it could just be personal preference.