Nice article. I found interesting that I’m most of the times ending up with the same split as you while looking at things from a different perspective.
I keep the 20% technology/maintenance rule by the book, sharing ideas and decision making with engineering. I could even say co-owning that part of the roadmap with the head of engineering.
Then I keep two lanes which I call “Epics lane” and “Tasks lane” (the names are there mainly for communication reasons).
The Tasks lane takes UP TO 20% of the roadmap and the size of it depends on the value of the small stories that are in the backlog. I keep in there small feature requests, bugs and other stuff that would quickly move things forward.
In the Epics lane live the things that change the experience of the product.
I also liked a lot your last point “staying in touch with details that give an “awesome” effect to your product”.
Thanks for sharing.