I’ve been using Git since I started at Moodle, but it wasn’t until I was using it all the time on my own sites that I realised how awesome it is. For example, I have my business site in Git, and have started work on the site as it is on the server. In the mean time, I am experimenting with an alternative version of it. This is in the same Git repository, just as a different branch. I can swap between them at will, with little effort and no conflict, and zero chance of losing any of the code I have written. To do this with any of the other systems – CVS or SVN for example – would be difficult if not impossible.
The freedom this gives me to work on a new site design while maintaining an existing design, then swap over with no down time, is amazing. It changes the entire development workflow I had been using previously. It also means I can store client sites in one git repository, with each site in a different branch. Then I can just checkout the different branches for each site. I’m not 100% sure how good an idea it is to mix clients sites like that, but it will work.