RushN and I both put the hd650 and he400 to the test. He ended up with the he400 and I chose the hd650. It's all about preference and what you personally find musical, engaging and enjoyable. I personally have found that I like a very dark signature and the hd650 delivers this well. I appreciate it's technical abilities and supreme comfort. I also give homage to the hd650's ability to scale up so well with better amps.
I do miss the he400 and regret that I never got to try it with the lyr and bf. I know that I wouldn't like the he400 r3 though. It's hot treble would be too much for me. Maybe there will be an r4 or I'll just buy an r2 when I have a little extra money.