I’ve streamed 4K HDR from Amazon, VUDU, and Movies Anywhere, and it looks great. Definitely better than a 1080p blu-ray and almost as good as a 4K UHD disc. But I’ve yet to stream anything from anyone that sounds as great as a disc.
Still, if you can stream 4K HDR, just do it! I remember the old days of trying to rotate the antenna on the roof to make the picture stop rolling, so I think all this streaming is great!