The difficulty has gone sky high its earning was $100 a day 10 days ago and now $30 a day and declining fast
dont buy one as its a door stop in november 2017
1450$ for a D3 , 30$/day still less than a 2 months ROI

around 7 weeks
as of today 9-30-2017If you can make 15$/day the roi still going to be less than 14 weeks

(3.5 months)
i would say that is still great ROI time

Those figures don't sound too exciting because they'll be more D3 batches released and the ROI will be extended. I assume those figures are for mining Dash. It might be better to mine a different x11 coin. The difficulty will be lower and if you end up with a successful project, you can make a lot more money than mining Dash.