I'm a Beyer fan, and first of all, I disagree with the lack of midrange comment. Recessed, yes; "none to speak of", no. Maybe after you've been numbed to midrange by Grado headphones shoving it in your face all the time...
Secondly, in answer to the original question -- no, I've not heard them, but I don't understand the appeal, and am not at all drooling to try them, though in all fairness, I should still hear a pair. The DT770's are fine for what they are, I'd be surprised if the changes really rendered an overall improvement.
I guess what I'm trying to say is, I'm skeptical. I suspect it's a flavor-of-the-month thing again, over there.