I have a pretty customized setup--Dvorak, caps-lock remapped to control, vim a custom vimrc and set of plugins I'm used to, etc.
It's certainly a mild annoyance when using someone else's computer, but in practice, seldom do I actually need to use someone else's computer, and even more seldom that I need to do development work on someone else's computer. It's usually helping someone out real quick, in which case it's easy enough to just deal with it. If I had to work on another machine for an extended period of time, it's easy enough to copy over my settings.
It's certainly a mild annoyance when using someone else's computer, but in practice, seldom do I actually need to use someone else's computer, and even more seldom that I need to do development work on someone else's computer. It's usually helping someone out real quick, in which case it's easy enough to just deal with it. If I had to work on another machine for an extended period of time, it's easy enough to copy over my settings.