I was able to grab the 4K 35mm FOTR theatrical so far. Here are some screenshot comparisons between the 35mm and Blu-ray theatricals: https://imgur.com/a/zEEoWR6

In my opinion, I love the colors and gritty feel (noise) of the 35mm. However, I feel there are some loss in details, especially in the black crush areas. You can see that in some brighter scenes, the details are better than the Blu-ray theatricals, like more depth in the grass or buildings. It’s hard for me, I like both, can’t decide between the two. I guess, it depends on the mood.