Vocals not forward enough? The HD650's are known for their non-fatiguing mid-centric sound....
Yeah, it all comes to to your experience with other headphones I suppose. The HD650 is warmer and lusher in the highs than what I consider perfectly neutral, but again, neutral point is debatable from you to me.
The treble extension and air and volume is certainly more present on my HE-500's which I would consider more neutral than the warm tilted HD650. Even people who compare both the HD600 and HD650 note that the 600 is the more neutral of the two, and the 650 is more relaxed and a little darker.
Please keep in mind, I do enjoy their sound very much and appreciate the signature and fatigue free listening experience, this is not a knock on them.