This is impressive, since you are stating that it will in fact use a 3-way crossover.
The E500 and Triple.Fi have three drivers, but only a 2-way crossover configuration, while the 2 bass drivers are configured differently internally to yield different sound frequencies (I'm not exactly sure how that works, but that's what they say).
And if the price is in the mid $300s with the legendary UM2 comfort, that's very impressive.
Now you just have to do one last thing.... no way would I spend $300-$400 without them having user-replaceable cables. I've had way too many issues with cables in the past, and if it weren't for them being replaceable, I would have lost lots of money to IEMs (having to buy new ones or sending them in for repairs). I hope Westone takes this into consideration. And I'm not the kind of person who is rough with his equipment. I take extreme care, always keeping headphones in their case when not in use, often leaving them outstreched to avoid curling and kinking, and I never do anything "active" when wearing them.