I would prefer sass and haml honestly. Other then that, I love how you make those mixins that seem very useful and I can see myself using it.
Videos are very good and show what are main features.
Thanks so much for leaving feedback - really appreciate it. It helps a lot, and thanks so much for your kind words as well. Just out of curiosity, why would you prefer sass and haml? Have you tried stylus and jade? If not, you should give them a shot!
You're definitely right that there are a lot of alternatives - I just think roots is the best. If there are any other features that you can see as helpful, by all means let me know and I'd love to try to integrate them!