My opinion:
From KnCMiner's website for the Neptune miner: "Shipment begins in Q1/Q2 of 2014".
That's not very precise and mining difficulty is increasing all the time (every 10 days or so).
https://www.kncminer.com/news/news-69So, I would say, you are selling shares of the miners because you don't know yourself when exactly you'll receive them and how much you'll be profitable mining with them or even profitable at all given the mining difficulty increase we have seen in the last months. You're even smart enough to say that you'll stop mining when you costs aren't covered anymore so that you won't lose money. So, with this, you don't risk anything while customers take all the risks upon themselves involving the risk of not having any ROI at all.
Am I mistaken about it?