I'm with you. If I can't either take the custom config with me (.emacs, for instance), and it goes beyond a few simple things, like changing a couple of defaul

I'm with you. If I can't either take the custom config with me (.emacs, for instance), and it goes beyond a few simple things, like changing a couple of defaults on OSX, I just don't mess with it anymore. It's not worth the overhead of either having to use an unfamiliar configuration in other contexts or having to spend the time to completely reimplement my custom tweaks again (which might not even be possible due to IT policies).