I don't find the upper midrange of EXT to be a problem for female vocals, and I say that as someone who doesn't mind the aggressive rise to a high peak that Odin has in that area (coupled with the leaner bass which can accentuate the upper midrange). I'd call EXT a light U shape for my hearing and music (FYI I can still hear up to ~17.5 kHZ when I got tested last year), and I agree with what @aaf evo is saying below about a U shape, and I can hear the upper treble/air/sparkle a bit higher than the upper midrange. The U doesn't bother me, it's kind of a light U from what I can hear when I listen to a band that has female vocals + cymbal splashes/riding all happening at the same time. FYI I listen to a lot of female vocal bands, a few male vocal bands, and tons of electronic music. What I consider a "W shape" in my collection is the UM MEST Indigo FWIW.
I think maybe I'm not understanding the term "u-shape" correctly as there's enough qualified consensus that EXT falls in that category that clearly I'm not using the term or explaining myself right. Basically the point I would emphasize as far as my perceptions go-- skewed towards the lower mids that they are-- is that I don't hear any element of EXT's mid-range that feels recessed behind, veiled by, or forced to take second fiddle to the bass. There is a massive bass presence to be sure but I don't find it ever dominating the sonic spectrum or grabbing my attention away from the mid-range, which is where my attention seems to be focused most of the time while listening to EXT.
Anyhow, I really love so many things about EXT such as the quality of the bass/mids/treble, and that the treble extends pretty high up. The bass quantity is an amount that I really like, and I prefer the bass overall (quality + quantity) to even the IE 900. I also like that the size of musical notes on EXT is on the larger side (kind of like Odin). Listening to distorted electric guitars with EXT's thick sound is so satisfying to me.
+1
Early days for me yet but my previous suspicions that EXT would emerge as the manifestation of all my IEM dreams rolled into one seem to be well founded.