Never heard the Tia Fourte, but from what I heard people say and other review, it is different sounding as the Atlas is certainly has strong bass.
Seems like The Fourte is closer to the Andromeda but with nicer overall bass rendition among other technical improvements.
Since The Atlas is basically a super Vega, you may find this comparison interesting, as is done by Twister6
"Fourte vs Vega - Fourte has a wider soundstage while Vega has more depth; both have a similar quality of sub-bass rumble, while the quantity is more elevated in Vega, and the same with mid-bass which is a little faster in Vega - it has more impact with a stronger punch. Lower mids in Vega have a little more body, while upper mids are pushed a little back in comparison to a brighter, more revealing, more transparent, and more forward mids of Fourte. Fourte treble is crisper and has more airiness. These have a noticeably different signature with Fourte being a little more mid-forward while in relative comparison Vega is more L-shaped."
Like you said, it is really expensive, I would never spend that kind of money on a set of IEMs, diminishing returns hits extremely hard at this level and I prefer to spend big on desktop setup with desktop amp/dac, or maybe invest my money elsewhere.
The Atlas itself is already expensive, however it looks like a great deal compared to the Tia Fourte or even to the Legend X.