*performs miracle*
Did you know your X900F can do 1440p/120hz? You just have to force the resolution in the amd/nvidia control panel, takes 30 seconds. It also reduces the input lag by 50% compared to 4K@60 + HDR, 13ms I think. Not as good as your monitor I'm sure, but getting there.
So you can have lower input lag, 1440p/120hz, a bigger screen, HDR AND possibly better response time. More on that below.
I just checked your monitor out and its response time is 4ms (grey to grey), while the X900F is 3ms, but I'm not sure if thats the grey to grey time because 10ms is also listed for X900F's "100%" response time. So you would also have less ghosting of certain colours in the image - not that you will have much on the monitor anyway - due to the TV being 33% faster.