Its not the best idea to just use someone elses calibration, each display is different the way it spreads light, intensity etc and your monitor changes over time. You should make a new profile every month. If you want your monitor calibrating buy a gretag macbeth, the calibrator is £100 or you could buy the whole kit with the paper calibrating kit and the screen calibrator for £1000 and its an awesome piece of kit.
Also every profile is different for each different graphics card you use.
The only part that is true about what you said is that each display is different in the way it spreads light. Also some people might calibrate it wrong by not setting the correct brightness setting first before calibration and things like that. And of course you are correct about differences in graphics cards, but these days they all output the almost identically (for 2d) thanks to standards in digital output. The differences in output was more something we dealt with back in analog VGA days.
But you are completely wrong about how it changes over time. That is only true for LCDs with CCFL backlighting. Because the 27" uses LED backlighting there is no changes over time, they stay the same throughout the life of the display (which is a lot longer too because of the LEDs). There is no need to recalibrate every month with LED.
Still I definitely would recommend people be aware that other profiles might be incorrect. Then again, someone doing their own calibration with their own calibrator might still result in incorrect color profiles. You really need to know what you are doing to get the most of them.
