Once you learn the quirks, you can ignore the dialogue. But many less common ex colon commands are missing, or have incompatible implementations. I use these commands a lot, and it took a while for me to get used to the differences. Keystrokes can be rebound, but mouse-clicks cannot. The copying policy is clouded.
Some xvile differences are big improvements over standard vi.
This differs from standard vi, where the text goes away on a file change. Another annoyance of standard vi is gone. You don't have to write your buffer to a file whenever you change windows. Don't abuse this unless you really trust your local electric power company, and your kids don't ever kick the power switch, or unless you don't mind enabling automatic save to disk. But it is a nice touch, when all you want is a quick look at another file or two or three or ten.