Moe has some good points about maintaining these instances, keeping things up-to-date, and launching more sophisticated infrastructure beyond your vanilla Rails/MySQL stack apps.

In my experience, Chef is really not that difficult to get setup, especially for the benefits it gives you: idempotent recipes with a great deal of control over the configuration, setup, and control of your infrastructure.

In the blog post, it mentions having to comment out migrations that will fail. That's bad: when bootstrapping machines, a db:schema:load is far more appropriate and less brittle.

Rubber seems like a half-solution for maintaining infrastructure. The blog post mentions that it was picked to prevent having to manually configure boxes, but it sounds like they chose a tool that only half solves their problem and then leaves them to do manual maintenance.

Now, with some experience, I can get a Rails machine booted and running an app in 20 minutes total with Chef. It's really pretty easy, and having tons of resources, lots of recipes, excellent support, and a sane system makes it super flexible.