It's a golden ears thing -- those of us who aren't super-sensitive to sibilance (yes, "us" means including me, meaning that I'm not sensitive to sibilance, not that I'm a golden-ears) like airiness and detail. And yes, I agree bright, and a shift towards treble can induce an illusion of air and detail, but think about the converse of that statement as well -- a pair of cans that do have gobs of air and detail will sound like they are shifted towards the bright and treble-y, too, although it won't necessarily be an illusion. Yes, agreed. Uh...no. The GS1K -- although by far the most comfortable Grado headphone in the stable -- just wasn't anywhere near what I want to spend time listening to, that I have absolutely zero intention of ever listening to that headphone ever again. Although I'm still dying of curiosity of what an accurate frequency spectrum measurement of it would look like. Also, I'm not joking, although I wouldn't argue with the stance -- in addition to what you said -- that there's quite a bit of variance among these. I believe one could get used to them, then all other headphones would sound bizarre.