I've played mono-Roots in ELO recently and I've been enjoying a pretty solid success rate.
I've seen a lot of complaining about Roots been wrecked by bans, but SoA is such a fearsome bonus that even cards not often used, like Amanie or Jerry, are still forces to be reckoned with in the right situations. Also, no-one seems to be fielding many Stop: abilities because Roots and GHEIST aren't such major players, so Roots are even better.
I can only attribute these complaints to a lack of imagination on the parts of players who seem to think the only options are to use the clan's best cards or not to use the clan at all. There's a huge difference between unstoppable and unplayable, and Roots are in between, not swinging suddenly between one and the other.