!rant
There are so many options to pimp my linux system. Is there any point in time, where I will be finished customizing/prettifying my linux? I highly doubt.
BTW.. what is the best way to backup the whole config? (color schemes, themes, gnome extensions)

First of all, no you won't.
Even if you think you are, after a few months, you will feel the urge to remake your config.

Instead of backing up the actual data, I'd automate the install-process, so you only have to execute a script on a new system, and it will configure everything how you like.

git repo