There were several reasons for choosing bootstrap-sass. For one, lots of readers recommended it. Moreover, in an introductory tutorial, I wanted to stay as close to the default asset pipeline as possible, which meant erring on the side of Sass. I also personally have a lot more experience with Sass (although, to be fair, LESS is very similar). Finally, the author of the bootstrap-sass gem (Thomas McDonald) got in touch with me and assured me that he plans to keep it up-to-date as Bootstrap itself changes.