Speaking of Plan 9 and Vim, readers may also find interesting the Vis editor: https://github.com/martanne/vis
http://doc.cat-v.org/bell_labs/sam_lang_tutorial/sam_tut.pdf
I admire Vis but at the end of the day a text editor is just a tool. When the investment into changing out such a tool becomes worth it is entirely user dependent.
[1] https://github.com/martanne/vis#non-goals
[2] https://github.com/martanne/vis/wiki/Differences-from-Vi(m)