Well, EE seems to make two types of IEMs (I'm generalizing): one type is all-immersive bass-centric and one type is more of a reference style.
The Zeus is certainly the latter, and I found it more "true" as a reference IEM than was my UERM. Even with the 1960 it was just transparent.
The Odin has more thump and thud, but it also has that transparency. I wish it had 3% more treble at the very top sometimes, but that really depends on how the music was mastered and mixed. For the most part it's perfect. I'm using the stock cable as the 1960 took away some of the treble (though the lower registers sounded glorious).
I really like it for the wideness of the notes and chords, it seems to handle lower and upper at the same time really well. Placement is wonderful. It doesn't have a giant soundstage (wide or tall), but is plenty big enough for my purposes. If you find yourself wishing your Zeus had more oomph, it will make you happy. Vocals are about the same as with the Zeus, just slightly more bottom end to them. They just sound "right."
My biggest concern with it is that I keep turning it up because it will go loud without fuzzing or sounding generally crappy, and I find I am listening at too loud a volume. I have to use some self control and keep that level down a bit.
It does need more power than does the Zeus to drive. On my AK1000 the Zeus at 50 sounds great and doesn't cause me concern for my ears. The Odin is at least at 75 and often 85.
I don't know if you ever tried the Phantom, but it tried to do the same things and, to my ears, failed. It had a great bass, but it seemed like everything was tuned to darker/warmer, and vocals didn't sound right. Trebles were really cut off as well.
The Odin just seems like a Zeus with body while still having a lot of transparency. I'm certainly happy with it.