Out of curiosity, what behavioral differences stand out to you between nvi and vim? NetBSD ships with nvi and it felt quite alien to me after vim and evil.
I used to believe there was one significant command difference but I am no longer sure it matters and frankly cant recall what it was even. There is a difference in how they handle the undo/redo stack, there are some differences in :.= and ^g handling. The flip to alternate brace pair behaviour is different but can be configured in vim. I think expandtabs processing is different. Nvi is far smaller but that obsessional view is less important in these days.
Nvi has no syntax highlighting and is far less scriptable. Again, it's minimalist religion.
