You're assuming they are perfectly rational, and have remained perfectly rational during the measurement period for the ratio. If they were perfectly rational, they wouldn't have had orphans recently, because they would have anticipated the upgrade. The ratio tells you about their past strategies, which they might have tried and abandoned (or will abandon). If they were perfectly rational, there is no reason for the 16/35=45% difference in processing times (based on ratio), I would have thought that F2Pool has slower connectivity, so should be the other way around. If miners were perfectly rational, they would pay attention, in the same way, to the way empty blocks worry users. Data has much variation, and our estimates, by completely different methods, are actually surprisingly close (~10 sec handwaving, ~16 sec empirical), not necessarily contradictory.