I wouldn't be surprised to discover that their "in-house" custom, the "aero", is actually based on a triple.fi that they purchase and then cannabilize for the components of the custom. Supposedly those that have heard it say that it sounds like a UE...
It may explain the higher cost of the "aero" relative to the custom molding of universal IEM's, which is much more reasonable in price.
The triple.fi option of having it re-molded with an additional mid-range driver sounds tempting. The triple.fi costs less than the other triple drivers, like the UM3X and the W3. Also with the main criticism of that earphone being the sucked out mid-range.
One thing that's interesting about their pricey in-house custom is that it looks like it may use a fusion of acrylic and vinyl, like the ES3X, which would add to comfort. Not sure about that...most of this is conjecture on my part because there's so little good info about UM.
If I were ordering a re-mold from them, one of the questions I would ask is whether they separate the sound tubes within the ear canal portion. It looks as though they do it for the "aero", at least...