449 * 3,249,550 = 1,459,047,950 Projected difficulty on Jan 8, 2014 if current growth had been sustained from the beginning to the end of the year.
Here are some ROI calculations:
assume your electricity costs $0.15 per kWh and assuming a single miner uses 50 watts per hour to run.
assume a very steep .1 profitability decline per year e.g. difficulty increased to 10x the original difficulty after 1 year.
At difficulty 37.4 million:
over 12 months of running you would earn 692.67$. It will take about 1.64 months to pay for your miner, the rest is income.
At difficulty 100.4 million:
over 12 months of running you would earn 18.91$. It will take about 7.5 months to pay for your miner, the rest is income.
My data looks much different than yours. I also prefer to express return in BTC rather than $. Data assumes 20% increase in difficulty. Gain is calculated for each window of difficulty then added to the next window until difficulty reaches a point of BTC and electricity canceling each other out per period (Around 2,000,000,000 Difficulty). This is for one K16 miner (elec included). I'm already past ROI.
This is what I posted on 8 August, since we are now going around in circles. No ROI, IMO.