I believe one of the reasons the 12" MacBooks tend to be underestimated by people who haven't used or investigated them is the very low spec CPU GHz numbers, in the range 1.1 to 1.4 GHz. I never lose an opportunity to extoll the MacBooks when I see people underestimating its capability, but I realise I don't have a proper explanation. My understanding is that it is all in the turbo boost which is a much bigger multiple of the base speed in the M series, eg 1.2 turbo to 3.0 in the MacBook, compared to 3.1 up to 3.5 in the 13" MBP. Since turboboost seems to be so effective in the fanless 12" MacBook, why isn't more turbo used in the cooled MBP. As we know throttling due to temperature is not nearly as big a factor in the MacBook as commonly thought so similar should apply, to some degree in the MBPs. I'm sure there are very good reasons....I am just trying to increase my understanding.