During my recent DAC search I heard the Gungnir and a used M7. I also finally got to hear the beloved Teac UD-501 and demoed pretty much everything Headphone Bar sells. I also got to briefly hear the Chordette and some other units through speakers at a local Hi-Fi place.
I don't think I have heard anything else on the list except for the X-Sabre and Bifrost which I own. I nearly bought the PWD MK2 without hearing it when the price dropped recently, but I went with the NAD M51 as we have a dealer just a few blocks from here and I could demo it.
When I say I would rate one DAC over another it's really just a matter of trivial personal preference. I know I would be happy with hooking up the Bifrost or Gungnir from time to time and rocking out etc.
The thing I like about the NAD is that it just doesn't sound like anything else and doesn't exhibit any particular signature (Wolfson, Sabre, AKM) that I have ever heard. It has an unusual and hallucinatory realistic/unrealistic smooth and detailed sound that I am really enjoying. I guess I am set until the next big thing comes along.