That sounds really useful. We maintain a frontend framework that we implement across a number of products, Moodle being just one of them. It would be far easier for us to use a grunt file to compile the SCSS for us outside of Moodle during theme development and then just ship our compiled, minified CSS to production within the theme instead of having the SCSS compile on the production server when settings change.
I understand there are some downsides to this like not using Moodle settings variables in the SCSS files but I think that's a trade off I'd willingly accept.