Based on what I am seeing on my Z9 so far I am not that hopeful at this point it is going to ROI. There must be some secret place everyone else is mining that is getting them great numbers. So far I haven't seen it. Just hoping it will keep earning like this for some time or there is no way to get ROI. Bitmain tossing some crappy coupons at us was an insult.
I'm not sure what results you are getting but if I can sell my mined ZEC at .025 (lower than current price) then based on how much ZEC I mined in the last 24 hours (0.17894627) I only need 50 days to make back the 0.21924398 BTC that the miner cost. I know all of those variables will look worse over time but starting at a 50 day ROI is pretty spectacular in today's hardware market. I strongly suspect that even a very pessimistic view of prices and hashrate increase should still yield at least a break even.