Emacs and Magit

Spacemacs does this with their 'Layers' Feature.

http://spacemacs.org/layers/LAYERS.html

It provides a collection of packages and configs that are community-sourced. It makes it easy to get python support for a language that you are not familiar with, but still allow you to apply your own packages and configurations on top of it if you like. This really cuts down the time it takes to setup things like python support.

Spacemacs is based originally around Evil mode, but there isn't any reason why you can't use it in Holy mode.

When it comes to updates/copying the config around the important thing is your .spacemacs config. So when you setup a new workstation, you copy over the .spacemacs config, install emacs, pull down spacemacs git repo and then it will take care of the work of pulling down the packages from epel, melpa, etc. The spacemacs default page also has links for updating spacemacs and packages as well as diffing your .spacemacs file with the latest version.