Daily profit?
Z9 Mini @ 650-overclock hovers around 14k and 370w-from-the-wall - shows +-$14/day on WhatToMine, now. If Batch-2 start shipping in 2 days... and say some Batch-2 owners paid about $800 ($850, minus $250 coupon, plus PSU, plus shipping = $800'ish)... could mean a 2-month ROI. Say 3 months with price-drops/diff-increases.
So Batch-2 Minis should easily pay for themselves by Christmas.
I don't know about that, I mean, think about how much you were making when the Z9 mini first dropped on batch 1 or when you received it, compared to what you are getting now. NOT looking at $$$ value (ignoring the market price fluctuation), but in the 2 months since i've had it (June 22nd). the Zen cash daily returns have dropped from 1.4 down to .8. So that's about a 40% drop in returns in 2 months. Though the major drop occured when the Inno A9s came online.