establishing a local configuration for each developer, dev server, production...

I believe this is handled right in CodeIgniter 3 already.

http://www.codeigniter.com/userguide3/ge...ments.html

In my .htaccess I only need to add "SetEnv CI_ENV sandbox"

Thanks for the information. I had considered this approach but decided not to use it because it means we have to maintain different .htaccess files on each machine OR we must add this SetEnv value in the apache configuration. I prefer to have a local config which overwrites the default config in a separate file which we can add to the .gitignore list.