There are a few comments in this thread:
http://www6.head-fi.org/forums/showt...ht=blue+dragon
Also, I've gotten K1000s since then, and my perspective has changed a bit.
So, here goes:
1. I still like HD650+BDv2 soundstage, but it doesn't match K1000's openess and naturalness of sound projection.
2. BDv2 improves great bass definition and impact, without sacrificing the sense of ambiance is unique to HD650.
3. BDv2 also lets through more texture. For example, strings sounds less homogenized than with stock cable. I noticed that the HD650 still smooths over fine details a bit, but it could very likely be the fault my DAC1 amp. Been waiting for my Dynahi to be built for a long time now. The end is near

4. I want to reiterate that stock HD650 sounds unfocused.
5. Frequency balance is close to stock; I feel that this is very natural. The other replacement cable I've used, Silver Dragon, moves the sound towards SA5000 likeness. I couldn't stand the SA5000; but HD650+Silver Dragon was more bearable.