How does this correspond with buying ZCash outright 13 months ago?  Shouldn't this be checked against a pure buy and hold on the benchmark (ZCash).  I wouldn't think that it could outperform based on the difficulty increases, but I could be wrong.  I'm actually currently mining ZCash on a 1070 and still getting decent returns per day, but it does seem like my money would be better invested if I had bought ZCash initially instead of a GPU.