I tried it. First, thank you to the developer for doing nice clean work and donating it.

The reasons it doesn't work for me are down to the readers I have. It's fine that the minimalist menu is just an unmarked icon if you're under 25.

For those who are over that, and I deal with semi-obsolete tech, I needed to add a Page hierarchy to the sidebar of my current theme because the menus were too oblique or perhaps script-blocked; whatever it was, readers weren't navigating well. I also added links to child pages on the parent page because they would click that instead of the child links in the menus.

There is no option to add sidebar widgets, because no sidebar, so def. CSS required and then it would be a mess.

Also, I know narrow is cool and makes it easier for different kinds of screens, but I like it wider than what it is. I post photos, and this was reshaping my thumbnails (480 x 640) a bit to fit them in.

I loved the large header, my headers tend to strain at the boundaries of most themes allowances, and it worked with the random header plugin I use. So the top looked fantastic! Perhaps a smaller title font...

It didn't work with the infinite scroll plugin for some reason, perhaps the Automattic version would work.

That said, a version that remedied some of the above would definitely grab my attention. Looks are great, but it's about communicating and easy nav. for us ancient folks. I think there is a middle way, and you are on the right track with Opus in general, looks great!