I have Alex's O2 mk1, my 4070 and Omega with me for the weekend. I've been doing some switching between the 3 headphones on different tracks. I'm not volume matching but they all appear close in terms of volume. I think I have to with Al's ranking (Al, I think this is how you ranked them).
Omega
4070 (very close second)
O2 mk1
I wish I could put into words the reasons. I just find the first two more enjoyable. The first two seem faster with better dynamics. That's the best I can come up with beyond just liking the Omega and 4070 better. Sorry Jp, the 4070 is staying. However, if you want me to send them up to you to try out, no problem.