I'll add my vote that subl would be useful on Windows, though sublime_text.exe does appear to wait now, which is good.
It seems to me there's 3 things you want for good behavior as an $EDITOR:
- wait (sublime_text.exe build 2181 does this)
- always open a new instance (sublime_text.exe build 2181 does this, too)
- disregard session: never open previously open files, don't remember this session's files (2181 doesn't do this, which is sometimes a pain)
Combining these 3 things into a --one-time flag (or whatever name makes sense) might be handy.