I'm far from a headphone expert, but I'm inclined to agree 100%. I've no trouble hearing the treble, and it is clear as a bell. The headphones are not slanted towards the high end. To my ears, they sound quite neutral in presentation. The fact that they play deep does not, to me, make them bass-heavy or 'basshead' phones, etc.
Maybe its just my source, but they seem extremely well balanced to me. The Grado 225's I used to own sounded lacking in the bass, and sounded less neutral, with an uneven midrange/high end emphasis. The fundamental tone of them sounded flawed compared to the HD650s.
I'm confident that there are better headphones out there, and maybe someday I'll own them. But I could probably live with the HD650s as my only headphone if pressed.