Indeed. Different people, different ears, different sources, different perceptions.
Many of you find no fault in the treble, but myself, Tyll, Hachiko, WriterHead, and others seem to hear various degrees of edginess, tizzyness, grittiness, or graininess. Not by great significance, merely nit picking here, but enough to keep them from sounding silky smooth. I have a feeling it has to do with the 10k Hz spike in Tyll's measurements. Perhaps that spike varies slightly enough from model to model, I really don't know.
Regardless, the X2 is one of the best headphones that I've heard so far, very musical and engaging, and has amazing subbass.
I'm just looking for a more euphonic, refined, and ultimately smoother signature.
My sonic journey from here will likely be HD650 -> HE-560 -> LCD 2 -> Oppo PM-1, or some variation of that, funds permitting, as those seem to really fit my preference. Time to save