When I'm not using an IDE, I'm a vi user because it's always there. When my /usr on FreeBSD has issues, vi is in /bin. OpenWrt ships with vi. I honestly have no idea if Emacs is any better, but not being a default makes it a non-starter for me.
Do you really have that many occasions to work in an environment where you can't ask for/install a package?
Limiting yourself for such rare occasions just sounds wrong.
JOVE is tiny, and has implemented a huge amount of emacs. After you spend 15 minutes or so tweaking your .joverc file you won't even notice it's not GNU.