Today I've compared for an hour the 846s, the Andromeda and the Atlas, and I have to say that the Shures 846 are still really amazing.
For me the Andros are the best if we focus only in sound: very resolving and detailed, neutral but not boring at all, very open from left to right and probably the best highs I've never heard in any IEM.
The Atlas are worst of the three in my opinion: a bit dark for my tastes, with less presence in the mids, a bit congested from left to right (although with good depth feeling), too relaxed (even if in theory the highs extend more than in the 846s, they sound quieter). I didn't like it too much for their price.
Then the 846s (which I have for almost 4 years), yes they don't sound as detailed as the Andros, but they are close; the highs don't extend so far, but good enough to feel the details and avoid congestion, in fact I prefer the highs of the 846 for vocal music, because they don't dristract me and many times they sound a bit more... organic; they are not so open from left to right like the Andros, but they give me a bigger 3D feeling; they are more resolving than the Atlas as well; and really important, I can listen the Shures for hours (Andros are a bit agressive, and Atlast sounds boring for me).
Now, what it makes the Shures great compared with the other two is the combination of fit, seal and sound. I love the Andros, really love them, but after 20 days trying I can not use them for more than an hour, they don't dissapear in my ears like the Shures do. Isolation in the Andros is good, but in the 846s is just fantastic. Atlas is more comfortable for me than the Andros, but the sound is not my style, I miss some detail and air.
So after experiment with these guys, I will keep using the Shures 846. For now is without a doubt the best IEM I've tried considering all the factors. So returning the Andromedas, at this price I need to put a check in all the boxes and only the Shures do this.