I didnt either and stuck with just 4 ba for kind of my whole life (had a set of westone 3 way back when, 3 drivers, not a huge difference between the 3 and 4 setup), and single dynamic (which I still looooove, but are an entirely different animal)...all in all they're sort of much of a muchness, each brand has their own sound, but, but, but!
....there is some kind of voodoo magic when you hit the 8 driver point, 6 doesn't really do it, but once you hit 8, detail, separation and imaging jumps up considerably, like....a night and day noticeable jump, and these having a 4 way crossover and triple bore makes that difference even more noticeable (low - lowmid - mid/high have their own sound path which keeps their respective frequencies very very clean....kind of wish these were 4 bore with a seperate mid and high but cant be overly picky at this price point and i have stupidly narrow ear canals, Gary did a wizard job at making the 3 bores fit
) BUT, if you get 3 really good drivers with their own feed you could probably achieve a similar sound but they cant have a 4 way crossover so probably not.
I also know that by doubling up BA's in their chosen freq range you can begin to control where you want a bump for particular applications, like harder hitting bass for stage users/performing musicians, endlessly high top end for mixing engineers (JH Layla for instance) forward mids OR the opposite, a massive U shape for radio listeners, then utter flatness for mastering engineers etc These can all be controlled by choosing different types of BAs and varying their combinations.
The main reason for my buy on these was 1) as a daily, and 2) for mixing, my ie800 sound super fun with their U shape, like the bottom i swear goes down to about 10hz hah, and the now sold JH Angie with their flatness but a bit exaggerated top top end (and were absolutely huge, reason i sold), these are sort of massively flat. They have a very very similar sound to the angie being 8ba per side but i think the flatness of these customs has possibly a lot to do with the custom moulded shell. Cause there's no silicone or foam tip effecting the sound and no natural 1khz - 5khz ear canal bump getting in the way as these go so deep it bypasses all ear artefacts
If you have a store (we have one here in Melbourne called Addicted To Audio, in one glass cabinet they have I **** you not about $100,000 worth of IEM's from dynamic up to 12BA's per side, and I listened to damn near all of them
) go listen for yourself, get a range from 4-6-8-10-12 ba and listen to the same song through them all. Size to value to sound quality, the best ratio, 8ba's seem to be the sweet spot...I mean...if this company had made a 10ba fully custom...i probably would have bought them