I would have guessed higher, but it would only be a guess.  If you're right that it's that low, then why did Microsoft include the port in the Xbox One S, and why did they also add the IR blaster (that would have a lot less purpose if you aren't using the pass-through for your cable box)?  Seems to me that Microsoft's research deems it enough of a selling point.  *shrug*

I could very well be wrong. Some guys that own an Xbox One S(like the forum member in this thread) didn't even know it still had a HDMI-in port. But that is not empirically evidence hehe. I have to hand it to Microsoft though(and I'm a Sony guy), hats off for keeping the optical port and including UHD Blu Ray playback. I'm tempted to get an Xbox One S just for the UHD blu ray alone....

I wish Microsoft would have never started to use the word "Upscale". That word has no meaning anymore.

At best up scaling makes it SEEM like the lower resolution is native. It doesn't make it look any better...

Uncharted 4 looks that great on any 4K tv with an upscale, the One S isn't making it look any better than the tv already does.

And now the Xbox One S has become a PlayStation peripheral.

That is silly.

That same Youtuber has plenty of games with 1080p output setting (letting the TV upscale) and 4K Output(letting the XBOS Upscale) and the difference is substantial .

Console outputting 1080p the TV does a terrible job fitting the image properly, looks stretched even though its scaled by the TV. The XBOs S scales accordingly for 4K and has a sharper IQ as a result.

The XBox One S hdmi in is a hdmi 1.4 port. It does not accept 4K signals afaik. So yes you can hook up your old ps4, can't hook up your 4K sky box. Plus who knows what happens with HDR output from the ps4, probably not accepted or recognized. And ofcourse the XBox One S upscaler adds lag too.
For a cheap 4K tv you want to watch 1080p content on, I guess it's a good solution. (using the hdmi in)

In the case of a PS4/PS4 Slim....

The Input on the XBO S doesn't need to add 4K, since the image is not 4K and since the output stage is what upscales the image.

HDR is HDR, if Ps4 can pass HDR over hdmi 1.4, then the input on the XBO S is HDMI 1.4, so you get 4K upscale + HDR as the output on a title that supports HDR.

Lag? In this case usage: The input lag is preferable thru the console outputting a 4K format than BOTH the input lag + display lag of letting the HDTV process the image real-time . LCD's already have lag simply displaying a native signal, upscaling adds several frames of lag on its own compounding it.

Upscaling is always preferable before it hits the display. you want the display to simply display a native image.