Mink
Headphoneus Supremus
Well, I am pretty treble sensitive. I don't find the X3s to be sibilant or overly bright in the treble region. I find them to be smoother than my Denon D5000s, B&O BeoPlay H6s and AKG K550MKIIs.I wish the reviewer would have said more about the treble region of the X3's. I owned a pair of X2HR's and loved their PRaT and how good they sounded and would have happily lived with them as my daily drivers, but there was too much energy in the treble region so I got rid of them. I think it would have been helpful if the reviewer had gone into detail about the differences (or lack thereof) in treble between the X2's and the X3's.
Hope that will give you some perspective.