I have an Apple TV4K and a Sony X800 4K player connected directly to the 4K Samsung panel for video.
The Sony X800 4K player has 2 x HDMI outlets, so the audio outlet is connected to my UMC-200.
The Apple TV4K only has 1 x HDMI output so I get audio to the UMC-200 via ARC (back from the Samsung panel).
My cable box is only 2K so it has the 1 x HDMI connection to the UMC-200 which uses the audio and then passes the video onto the Samsung.
This all works pretty well but there are a few downsides;
1. Low WAF, as it requires changing sources on both the UMC-200 and the Samsung panel. As well as an inconvenience there can be an occasional issue with HDMI/HDCP handshaking, which requires a reboot.
2. Via ARC I get only Dolby Digital 5.1 from the ATV4K, which sounds like a big issue. But in reality it isn't as I haven't found any streamed programming that uses more than DD5.1 anyway.
3. I needed to buy 4 x 4K high quality HDMI cables, which in my case are 5 metres long. With a 4K switching processor I would have only needed one, which means 3 are going in the never to be used again box at some point.
I did try a number of "inexpensive" 4K switches but they all had some issue or limitation. There are "expensive" 4K switches that don't, but at more than half the price of an MC-700 I just didn't see their worth, and it too would eventually end up in the never to be used again box.
Bottom line, it was a temporary measure that I put in place a year ago while I waited for the updates/upgrades to the XMC-1. When the reality was I should have just gone out and bought an MC-700, used my 25% UFL, and got on with life.