Same dilemma here, I have my Xb1 which I game with, and a Marantz that used to connect both my HTPC and console via HDMI to my receiver, acting as a switch. What I've done now instead is just run a direct HDMI cable from both sources to the two HDMI inputs on my projector (I game from both), and use the 5.1 via optical on both my HTPC and Xb1. I think 7.1 is really not a very substantial difference anyway, and optical to my receiver directly allows me to listen to music while playing games, or even having the projector off when I'm gettin busy in the other room, if you know what I mean har har. HDMI for audio basically sucks because you lose the audio signal if you shut off the downstream TV or Display. 5.1 Optical is more than good enough, and though I agree it's a bit more tiresome to switch between sources like this, I really think receivers should only do audio, and you should have a direct connect to your display from your source, if you are hardcore.
I also sometimes wonder if a certified low-lag HDMI switch would work, but what it really requires is signal duplication, so the receiver gets the audio, and the TV or projector gets the videofeed, but HDMI doesn't actually work that way, your source will see the TV or Projector's built-in audio capability as 2.0 channels, and that will take precedence over the 7.1 that your receiver is capable of.
I looked up tons of switches that could accomplish splitting out the 7.1 audio into its own HDMI feed, while keeping the source funnelled to my projector directly, however it won't work due to the HDMI spec. E.g. I had my PS3 outputting 3D stereo, but my receiver wouldn't pass both 3D and audio at the same time, due to it being HDMI 1.3 and my receiver only being HDMI 1.3. So even with an HDMI 1.4 switch, capable of passing through 3D + 7.1, it still wouldn't work, because the lowest common denominator of your downstream device capabilities is the one that gets sent back to your original source. Meaning, in your case, even with a switch or a splitter, your TV's 2.0 channels of audio will tell the switch it can do 2.0, and that will combine with the 7.1 capability from your receiver to tell the console or HTPC, sorry dude, you only have 2.0 channels of audio, have fun!
HDMI = worse POS spec ever. Whoever designed it should be dragged out into the street and shot. As it is, if I want to watch a 3D movie with surround sound, I have to use optical and the 3D directly to my projector, even if I bought an expensive HDMI splitter or switch, it wouldn't pass through 1.4 3D to my projector and the 7.1 audio to my receiver, because my receiver doesn't support HDMI 1.4 and the signals are different. When I look at the audio output on my HTPC, if I plug it directly into my PJ to do some 3D, I can only play back 2.0 channels, so I have to use optical.
They really need a new optical spec for 11.2 channels at 24/96 or even just 16 / 48 (more than good enough for human hearing). That's why I say screw receivers, just wait for WISA speakers with 7.1 24 /96 uncompressed with no lag, directly from your source transmitter (with lots of direct inputs), and say goodbye to receivers.