IMHO both of the current incarnations of retina Macbooks are underpowered compared to the massive number of pixels they need to push. This is especially true fo

IMHO both of the current incarnations of retina Macbooks are underpowered compared to the massive number of pixels they need to push. This is especially true for the 15" while running on the integrated GPU, and the 13" all the time. HD Graphics 4000 just doesn't perform adequately for OS X on that resolution in a high end machine. The cooling solutions are among the best in terms of noise per cooled watt, they both pack a lot of battery and the latest Intel CPUs are very powerful. But if the GT-650M is needed as soon as you scroll a webpage I think that the advantage of the Retina display diminish. If you work mostly stationary the integrated GPU will face a great challenge driving both the internal retina display at the same time as an external 27" 2560x1440 display. That translates to a lot of noise and dust in your precious machine as the nVidia chip is needed all the time. I opted for delaying my upgrade to retina until the Haswell GT3 GPUs start shipping. When that might be is anybody's guess.