According to that spreadsheet I should get ~47BTC with the free upgrade and ~130 with the paid, which costs me 46BTC.
So if I go with the paid one I'll have 84BTC more at the end of the 9 months, vs. the 47BTC of the free upgrade
The problem here is that we have to decide being blind, because we don't know when or if this is going to begin, but in case we choose the paid upgrade, we have to pay the BTC on the following 5 days
I would like to say that I think the number is the spreadsheet are overly optimistic.
I would run your simulations with the following assumptions:
- It will take three months to ramp up to the 9mh/s per teramining contract after which time the 9 month clock will start
- I would plan on the network being 1,300Th/s by the end of the year
You'd need to figure in at least 50% growth in the network this month alone....