Yep. I've got one and after one afternoon's testing am quite pleased with it! *Much* less painful to the wallet to add this to my perfectly working 975 than to replace the 975 with a 976. I replaced a failing 1080P Vizio (early 2013) with a UHD Sony(late 2017 build).
I was going to replace my nearly 5yo Vizio with a new (2017) Vizio that SquareTrade is giving me (since the 2013 model is no longer available to replace the original TV), but the vendor they selected to provide the replacement TV sent me a DOA one and is dragging their feet on picking it up (2 weeks now) which they insist they need to do before replacing it. So I'm guessing at least
2-3 more weeks before my warranty replacement is finally here. So I went out and bought the Sony (end of model year and Super Bowl sale) and will just sell the replacement TV as NIB as soon as it arrives to help offset the higher cost of the Sony.
Anyhow the 42AVR switch setup is surprisingly easy if you read the install manual *very* carefully. I missed a couple of points initially, one of which led to my posting earlier looking for guidance on the ARC channel. The switch has six HDMI ports. Four are HDCP 2.2 inputs, one is an HDCP 2.2 output (this goes to the TV) and one is an audio only passthru that goes to the prepro or receiver. On my 975 I plugged it into port 1.
I connected the 975 Output/ARC port to the TV ARC port to 1) see the 975 menu and 2) provide audio for any TV based sources (OTA antenna, Firestick plugged into another port on the TV and any TV apps).
I unplugged all four of the devices i had originally plugged into the 975 and plugged them into the same ports on the switch that they had been on the 975 (975 port 1 to switch port 1, 975 port 2 to switch port 2, etc). I then went into the 975 menu (after switching the TV input to that ARC port) and changed all input sources other than AUX to Video HDMI 1 and Audio HDMI 1 (since that's the connection between the switch and the 975) and I then set the AUX audio to HDMI ARC (video setting doesn't really matter since AUX will merely be playing audio from the TV's other sources).
Oh, and I received mixed opinions on plugging my HD devices into the switch vs leaving them on the 975. I ended up plugging everything into the switch just to make programming the Input Sources and future upgrading easier.
Both HD and UHD sources look great, no indication that there's anything extra in the signal path.
I apparently swapped 2 inputs lines by accident, so I had to update my universal remote, but everything else ... simply works!