Thanks for the feedback and suggestions. I bought both pairs used, but they are still fairly new so I would guess they are both the newer versions. And the difference in sound is incredibly slight, so I do not think there is anything wrong with either pair. I can make myself crazy trying to sort out what I am hearing, and then the next day, my preference will shift and what sounded better will now sound worse.
I like how you said that these headphones give life and body to the details. That may be what I am hearing in the warmer pair that is more broken in. I actually like the sound of the pair with over 100 hours on them better. It is a smoother and less fatiguing sound, and still has plenty of detail. My only criticism of these phones overall is that they can sound a bit congested on large scale music, which is maybe why I said the sound sometimes seemed a little muddy.. Maybe that is just the nature of closed cans. Otherwise, I love the sound of them.
Anyways, I sent the more broken in pair off to be recabled and meanwhile I will see how the other pair settles in. It will be interesting to see how a silver/gold cable affects the sound.
Edit added: I had been listening on my portable setup (Tera-Tralucent T1) and I just went back to listening to the ESW9 through my desktop setup (Tera-TDS202 Sound Enhancer-iCAN amp) and there is no congestion or muddiness in that setup. The combination of the TDS and the iCAN makes for a incredibly clear and open sound with great instrument separation. I keep hoping I will find a portable setup that sounds as good, but in the meantime, these phones sound very good with my desktop rig.