Anyhow, my inability to decide between the cks1000 and IE80 led me to buy both (which I've shown in the embedded pic). Out of the box it wasn't even close--the IE80s were equal or better in every way, with the possible exception of bass punch. Other than the rich, controlled bass of the cks1000, i found that phone to be a total mess.
However, the audio technicas are rapidly improving on the higher end--much more clarity and overall quality (though there is certainly more sibilance than on the Sennheisers). As others have noted, i am quickly becoming a believer in the cks1000s. In fact, i find myself reaching for them as much as the IE80s. That bass is just soo satisying, yet cks1000s are far more than fart cannons at the other frequencies. If forced to choose, i would pick the Sennheisers. However, i am pleasantly surprised by what a close contest it is (and the cks1000 gets better by the listen).
Of course, i am a lowly, mouth-breathing hip hop afficianado with no graphs to support my thoughts, so take what i write with a grain of salt.