https://www.computerbase.de/2018-07/hdr-benchmarks-amd-radeon-nvidia-geforce/2/
AMD takes less of a hit when doing to HDR at 4k. they test a few games a saw that AMD loses 2% while Nvidia loses 10% on average, that would make a Vega 56 better for 4k HDR gaming then a 1080 at the same current price point.