Huge fan of salt stack, and I may push Adrian in that direction. The changes we made here were minimal in the way he deploys, and with so many architecture changes behind the scenes, we decided less is more on that front.
Salt is more easily repeatable across heterogeneous environments.
For example, we're using Salt to manage our development, testing, staging and production environments. We couldn't do this with AMIs, since the environments are quite different.
It makes updating quite easy, as you don't need to create a new AMI, just push your update to your release branch, then run state.highstate from your Master.
If you configuration changes, you update the master and then you can push that change across all (or just one) of your environments.
