I recently ordered a 50GH/s unit that I would have (optimistically) wanted it to pay for itself in 3 months (delivery date November). It would appear now, with projections and the almost 50% increase in difficulty recently, that the trend for a 50%+ increase will continue. Especially with the time solving/confirming dropping from 10min to 5min.
It would appear that I won't ever even break even with this unit that I pre-ordered.
How accurate are the predictions that the difficulty will be at 178mil by November 2013?
The 35% increase (not 50% !) was just an excess, I expect normal increase around 20-25% per retarget and slowly decreasing over time