Your ROI is all wrong. You are wanting to get BTC for BTC. You said that right now you get 4.2BTC/day and it would take you 20 days to get that back. Your looking to get back 80BTC that equates to at todays rate of $230/btc or $18,400 when you paid 80BTC at $16 you paid $1,280.
BTC is worth what it will buy and a 1 BTC today will buy a lot more than 1 BTC from 6 months ago. So you can't use BTC for BTC as your ROI. If the price of BTC stayed relatively the same then you could. So you have to use something else to determine your ROI say USD which does not fluctuate as much.
If you not happy with that ROI I would be more than happy to take the unit off your hands
BTC is worth what it will buy and a 1 BTC today will buy a lot more than 1 BTC from 6 months ago. So you can't use BTC for BTC as your ROI. If the price of BTC stayed relatively the same then you could. So you have to use something else to determine your ROI say USD which does not fluctuate as much.
If you not happy with that ROI I would be more than happy to take the unit off your hands
It doesnt make sense to take the exchange price into account. Simply because the following.
You invest 100BTC into an avalon. A BTC is worth $10 at that time. That makes the machine $1000. You earn 5BTC with that machine while the exchange price is $200. And you already have your investment back. But that isnt correct. Because you invested BTC. If you would have kept the BTC and didnt buy the Asic then you would now have $20000. So a miner has always to beat the buyingprice you paid in BTC. Otherwise you lose. Or you would have been better to keep your bitcoins and see the exchange price and the worth rise.
The same applies to Asicminer shares. If you got your initial investment IN BTC back youre fine. Otherwise you would have been better to keep the BTC.
Everything that is beyond the buyingprice is additional and can be calculated in whatever you like. But an investment in BTC has to come back in BTC.
This is what I'm trying to explain post after post in different threads. Is incredible how people keep saying "hey, you will get your ROI faster because BTC/USD is skyrocketing", and then they do their math in USD... When speaking about an Avalon #3 which has been bought with BTC.
Guys: you spend BTC, your ROI is in BTC. Otherwise, as Sebastian says, you would just have been better HOLDING those BTC.
Pure logic.