If colour grading is no different then it /is/ washed out because that's what the colour grading is doing to get the intended art style
HDR just makes the emissive light sources pop more.
Edit* I just tried gain with HDR but this time ran the calibration for HDR again as have not done that since getting the replacement, no idea why this would make any difference since the profile is still the same as is the hardware lol but now the HDR mode looks more crisp than before, it s a little less washed out but it's still there, just more punchy now. Of course black isn't black due to the art style so there is that still...
In HDR, the level of destruction inside the mansion always amuses, it's great fun just shotgunning around