Mining Hashrate Profit Guidelines

[BTCThousandaire]

Hashrate Bitcoins produced in one year
333M .25
1G   .87
2G   1.78
4G   3
5G   4
8G   6
20G   18.1

This should be a reasonable or optimistic mining projection.
So total costs should not exceed these numbers for the year starting today.

Using:
Bitcoin = $100
Difficulty growth/Month = 80% or Difficulty growth/11 days = 29%
mining.genesisblock calculator
Current difficulty of 37M on August 5 2013

Using my own calculations, Bitcoins generated every 2016 blocks, at 20% difficulty increase(about 11-12 days), produces 5x that amount in a year.
At 29% it is 3.45x. This differs from the genesisblock calculator, I don't know why, but I used simple geometric series calculations so I must have missed something. Maybe someone can point out the difference. Anyways, their numbers are more optimistic.

Losses adjusted for n months delay to start mining, per 1 GH
1 months .4   46% loss
2   .62   71% loss
3   .75   86% loss
4   .82   94% loss

[DigitalHermit]

Losses adjusted for n months delay to start mining, per 1 GH
1 months .4   46% loss
2   .62   71% loss
3   .75   86% loss
4   .82   94% loss

I think this last bit is the most interesting/useful for would-be miners to understand. It is the reason people become absolutely livid with delays from BFL, Avalon and any other ASIC seller as delays rapidly destroy any potential for profit (other than profit for the mining equipment companies of course). 

I imagine in the future that more savvy miners (unlike the current math-challenged crop) will demand a purchase contract with built-in discounts off the agreed purchase price to offset any delay (46% discount for 1 month delayed, 71% discount for 2 months delayed etc...).

I, for one, will never "pre-order" mining equipment without such a contract in place or without the funds being 100% in escrow to make a total refund possible if/when a shipping date slips.