I surprises me too tbh. The ZN1 Mini is nice, but personally I still prefer my original ZS1 (with brass ring and crossover, both removed in the current revision) by a large margin. The ZN1 sounds veiled. The ZS1 is stupidly bassy yes, but despite that it's very clear, has lovely mids, and sounds a step above the rest of the ZS series. Well, except for the ZS3.
When I tried to inquire about the ZS2 with the only person I know of who had it, my inquiry was met with rabid and aggressive disrespect so I'm left thinking it's going to sound like the ZS1 (current revision) and ZN1 Mini which sound identical.
There are a couple reviews up for the HDS1 (including mine) but the majority of comments simply revolve around them being one of the more neutral KZs. HDS3, well, I don't like how they sound at all. Muddy, overly mid-bassy, lacking clarity. Just blah. At least they're better than the HDS2 which takes all those negatives to another level, though it does have a good soundstage in it's favor.
Comments on the EDR2 are mostly varied from what I can gather.
The ED3 is all over the place too, probably because there are too many variants and unofficial names. Basically comes down the ED3 Perfection (i.e. original) being neutral-ish with a treble-head tilt, and the ED3 c/Acme/Youth being warm and somewhat bassy. I know there was one other variant, but I can't recall off the top of my head what it's called or how it was supposed to sound.
If you found the EDR2 too bassy, the ZS3 is a bass cannon in comparison (imo).