As you can tell from all the replies there is zero to worry about Dolby vision on the XF as I play mostly UHD BD discs for HDR and DV and there as never be an issue, basically blow away how detailed the picture can be with HDR/DV.
Then I watched some DV on streaming, what a mess, the Witcher had a lovely black elevated hue to the whole programme it got that bad that on episode 4 I turned off and before that I watched the new star wars Mandalorian and while it was a good picture it was not HDR in any sense of the word. I have now gone back to normal 1080p without HDR for streaming and to me its looks lovely and looks more HDR than HDR because of the very poor mastering of some of the shows.
You maybe aware that there is Dolby vision dark or bright on the XG and above as I have no idea if that does anything meaning full as I never tested it, but I would of thought if it was mastered poorly to begin with, then it will not make it any better.
For the prices, the XH as not come down in price yet, that will be closer to the end of the year as the XF and XG are basically the same, with the XG having a faster processor and may help for streaming via the TV, but if you use an external source like myself then they are the same. The XH does have HDMI 2.1 with adaptive sync which will be useful if you plan on getting any of the new consoles PS5/XBOX series X otherwise it will not surprise me if its still the same amount of dimming zones etc…, as seen on the XF.