No, but from everything I've heard it's still laid back in terms of the upper frequencies being congested. If the only difference is sound signature, I can fix that with EQ. But EQ can't increase the actual detail. I've heard that the whole HD6x0 line suffers from the same core congestion in the upper frequencies (10 and 15+khz) that make it effectively less detailed for instruments that use those frequencies (violin, guitar, etc.).
In fact I'm starting to think many people like this congestion, being the very reason they find them so smooth. Similar to how people like tubes -- they literally congest the sound signature intentionally. While I will be keeping my HD650s as nice easy to listen headphones, I don't like congestion in general. I have very sensitive hearing (I've never done a real test, but while some people can only hear fingers quietly rubbing together a few feet away from their ear, I can hear it easily across a large room), and I like to have hi-fi music, and congested is not hifi. That's another reason I find tube amps stupid, in the context of hifi (and yes, people always report SS less congested and colored, than tubes, from what I see -- correct me if I'm wrong). Tubes are fine for intentional coloration if that's what you're after, but I'm not on head-fi for colored sound, I'm here for hifi.
People say the HD600 is neutral but FR graphs show quite the opposite, with the HD650 being more neutral with perhaps more bass. But the problem with the HD650 is not too much bass, it's the lack of quality treble. I don't think the HD650 bass is much emphasized if at all -- rather the lack of treble makes it (incorrectly) seem like there should be less bass, but that just would give a upside-down smiley face FR.
The lack of strength in treble frequencies is not a problem because EQ can fix that and I'm not a no-EQ purist. While EQing the HD650 does make it sound much more natural and actually realistic for violin, guitar, etc. (it removes the feeling you're in a wooden box listening to the outside), it doesn't fix the subtle congestion aka detail aka sound quality in those frequencies, versus for example an SRH940's highs.
I've ordered a DT880 which will be my all-around neutral headphone where treble matters, hopefully. My SRH940 worked but my head is so large it broke the SRH940. I kind of doubt the DT880 will be as good with bass as my HD650 or as comfortable (I got to try a DT990 and it was a bit less comfortable than HD650s), so I don't ever see myself selling the HD650s. But I like to at least have an alternate headphone that does treble right. I may have to wait until HD800s though until I get one that does bass/mids/treble all excellently.