Since I started to use Vim, I can't switch to any other editor or IDE. It's not because Vim editor is so great or because I don't like those niceties that other editors and IDEs offer, but it's because I have those Vim-bindings in my muscle memory and I can't be productive w/o them.

Show me an IDE that has nice support for Vim-bindings and is highly customizable (plugin support with rich API, programming language I can use to improve it as I like it), and I will happily leave Vim and use it. So far the closest thing I've seen is Lighttable, but still it lacks some Vim-bindings and is very in beta for now.

To answer OP's question, Vim-bindings and configuration options at extreme.