Coffee from Sumatra was once considered "inferior" because the "semi-washed" process left the beans looking rustic, and with remnants of the mucilage, dried on the bean.
However, once roasted this "defect" gives it an earthy, malty flavor, pronounced body, and lower acidity. In the 90's, we liked Sumatran so much that it was always a part of our Potrero blend. Stay tuned, you may see it make an appearance in the future!