I don't foresee the dev and production environments ever deploying to the same part of the filesystem. I agree with Dave that there doesn't need to be a dev bias baked into the code. I would go further and say that there also not be a prod bias baked into the code. So the only solution is to remove that default from the source altogether.

I'm also inclined to update both the dev and prod script to insert the appropriate (different) row into config.js. Does anyone have any qualms with this? I realize that many core installs may not care where the keys are, but we have plenty of stuff in config.js that might not be relevant for all installs.