I pretty much agree with your comparison after spending several hours comparing both. I would just say the bass on at least the 4z I tried had more impact and a touch more detail. I do think the 1266 is a slightly better all around HP, but If I had to go for one it would be the 4z. The comfort on the 1266 TC was a problem for me and I spent a good amount of time adjusting it according to videos I have seen. Also, the timbre was a touch funky in comparison with the Utopia and 4z. I might chalk that up to maybe me not being used to it?I have both and plan to keep both. Very complimentary headphones. The Abyss has the bigger more lifelike soundstage. It’s treble feels more detailed and airy. The faster of the two. The LCD4 has the sweeter midrange. Bass on both is fantastic but different. The Abyss is tighter and faster where as the LCD4 is fuller with greater sense of impact. All of this is my perspective of course.
Now what bothered me about the 4/4z was the classic Audeze Upper midrange dip. That could clearly be heard in comparison to the other two HP’s. Overall though, because of comfort and fact that the 4/4z’s can be had for a lot less these days, lead me to prefer the 4/4z........for now. I have however been toying with the possibility of getting a used Phi or OG 1266 for a really good price and see how much I like it. If I do then happen to fall in love with it, I could always sell and upgrade to the TC, or whatever the new 1266 model is at the time.