I reckon their estimate for the next difficulty is too high (537 million, or 37.46% increase). I'm tipping a 27% increase, or ~495 million. The rate of finding blocks has stalled over the last couple of days so I don't see a bumper increase this time. Possibly this is due to most of KnC's first batch being delivered, and there being a temporary lull. It will only be for a short time, though (i.e., it won't be long enough to turn those unprofitable miners back to making ROI).