For a long time I have bought the digital versions of movies off of iTunes and have more recently been expanding my physical collection. I’m curious, how big is the difference between the 4K digital version of a movie compared to the actual 4K disc? If I own the 4K digital version of a movie is there any reason to also pick up the disc version?
I think it really depends on your gear/equipment and your own eyes/ears. Every setup is different (not just in screen and speaker quality but also in internet speeds and streaming apps). Likewise every person is different in what they’re used (what their quality standard is) to and what they notice.
Streaming 4K can range from awful to very good. 4K Blu-ray will look and sound leagues better than awful streaming but might look nearly indistinguishable and only sound slightly better compared to very good streaming and not overly picky eyes/ears.
The best is to test for yourself. I’d say if you’re unsatisfied with the quality you currently have it’s worth exploring, but if you’re already really content with the quality you currently have then maybe it’s not worth the extra cost?