An important point that was left out of the article is that LESS had much faster compilation than Sass, which was probably the deciding factor for it's use in B

An important point that was left out of the article is that LESS had much faster compilation than Sass, which was probably the deciding factor for it's use in Bootstrap. Now, there is libsass; a C/C++ implementation of the Sass compiler which brings Sass compilation up to speed with other preprocessors. My feeling is that the community has always regarded Sass as the better preprocessor, but easy of use and compilation speed matter held it back. But, as front-end build tools have become more accessible, and Sass getting up to speed with libsass (and dropping the Ruby dependency), I think it is becoming easier for projects like Bootstrap to start embracing Sass.