I just upgrade from SL to ML (skipped Lion). Much snappier, and it's got some really nice features. There are two "features" though that are really bugging me. 1) That I cannot run my external monitor, in it's native resolution, while keeping my MBP open. Now, opening my MBP triggers the native LCD, and if I'm mirrored, then the resolution on my external drops, and if I'm doing two screens, then I can lose my mouse. Also, the video card now is running 2 screens, which creates heat 2) ML just seems to run more CPU. The whole laptop is running hotter (by touch -- I don't have any temp gauges). I do use menu meters, and it seems to me the base CPU usage is much higher than when I run under SL. So, this 1-2 punch means that the fans sound like a jet engine all the time. I can keep my lid shut and cook the laptop, or I can open it and enjoy all the problems of not being able to shut off the laptop LCD. Am I alone on this? If I just moved to a more modern MBP, would the newer CPUs handle ML better without all the burn?