"micro detail" you say? ER4B, I say.
I've had a pair for a few years and I think for picking out the detail in a recording, these IEMs have few peers. They tend to be a bit bright sometimes, but I've not experience any sibilance. I feel the brightness is recording dependent.
If you decide to get these, make sure you've got a warm and powerful amp to pair them with. I've liked them with the MPX3 and the EC/01, but really like them a lot out of the RKV. They even sounded pretty darn nice out of a LD II+.
I've had a few ss amps in the past (Canamp, GCHA, Move, Hornet), but don't recall how they sounded with those. I'm assuming not great, or at the least merely okay, as I've absolutely no recollection of those combos.
They will take some getting used to, though. They'll sound a bit anemic at first. But then, once you're used to the sound, you'll wonder if there's anything better out there at detail retrieval. Just realize that, in the end, one person's "crystal clear" is another's "etched and bright."
I think there's one listed in the sales forum. And it's been there a while. I think resale value is pretty non-existent with these, so you might want to consider that before making a purchase.