I will also say that on YMYC (it's on Youtube) he also mentioned that the preferable "conservative" valuation was also shown to have a margin of safety when compared to actual market price in May.Once again this highlights the trouble RM has with relying on forecasts, happily this can create opportunity when those forecasts are missed. As long as the downgrade is not a permanent state of affairs.
edit: The point is that it isn't the analyst forecasts or the conservative earnings forecasts that you make up yourself, the fact is that the ROE method of valuation for mining companies (or those with lumpy earnings) just isn't accurate.