I would suggest Kanas Pro or Tin T3 plus, both bring more of what you like about the Dusk vs. Monarch and are considered well tuned for a wide range of genres.Does anyone know a equivalent to the Blessing 2 : Dusks in a custom IEM? Honestly if I could get these in a custom, they'd be my endgame tbh
Excerpt from Brent Butterworth's review of Tin T3 Plus: "Often when I first use a set of headphones or earphones, I hear some things that seem unusual, and I spend a lot of time trying to figure out whether they’re major flaws, minor flaws I can tolerate, or minor flaws that disappear with a few minutes or hours of use. When I first used the T3 Pluses, I didn’t have to go through this step because I quickly realized I liked them."
EDIT: Sorry missed the custom part. It's rather niche so it's hard to corroborate CIEM performance. May I suggest as an alternative that you try a handful of different universal IEMs, maybe with different tunings. You should find some will have better fit and seal for you as well as sound and might get pretty close to the CIEM advantage after picking out your best set.