Yes I believe you need to do the 444, 10bit and/or 422, 12 bit fixes.
If you don’t do this you will be outputting 10 bit HDR content in 8 bit HDR. Even though the HDR metadata is putting your TV into HDR mode, and the content is still following an HDR EOTF, the video output is only 8 bit by default and 8 bit bit depth is not great for HDR content, which needs 10 bit to preserve the original content…
I checked this with an HD Fury Vertex (which displays all sorts of HDMI diagnostic information), and without the command line instructions the HDMI output was reported as 8 bit only.
Am hoping to post more on this over the next few days.