[asagala]

I'm finding it hit and miss so far. In DirectX 9 mode films often don't play, while in DX11 mode they usually play on the first go, but if I ever have reason to stop a film or start a new one the next video plays in a 1/4 box in the top left of the TV only.

Quite weird really. I'd really like to know if DX9 or DX11 is the better mode; my Geforce 1030 will support either happily.
Also does this MadVR change the refresh rate of the TV to match the source material? I cannot tell if that is happening.

You have a 1030? I am considering upgrading to this card, can you tell me if you can enable 10 bpc in Nvidia control panel with that card. I searched the whole google without answers. It's the only thing holding me down from buying one.    

Better use a 1050TI, the 1030 is too slow and has too less VRAM for good madVR Experience   

 Not true. Using the 1030 and it works fine for 4k hdr. You just have to be careful on what you enable in Madvr