This is perfect timing. My co-founders and I are currently in the process of duking it out over these choices. Now we have something to break the tie.
I'm the author, along with @patricko. Feel free to chime in with questions here. I'll link to this discussion from the post too.
"Nobody used Stylus, sadly" -- Adam...curious why you say that?
Stylus is a CSS processor similar to SASS/Less, but without the punctuation. Last year one or two teams tried it, but this year it seems to have lost ground. :(