First, thanks for this plugin!
However, I find the "mix" with the "standard" IntelliJ editor a bit weird at times. For example, if the cursor is at the end of the line and I'm not in (vi) "insert" mode, hitting Enter opens a new line... this is not what vi would do. I then start typing the new line, but get unexpected results because I'm not in "insert" mode.
Also, I think I'm experiencing a bug with the x command when I prefix it with a number, e.g. 3x. It seems to delete n*n characters, where n is the numeric prefix, i.e. 2x deletes 4 characters, 3x deletes 9 characters, etc.