@LeonidKogan For me, the FR of the IN8 is perfectly fine for listening. IN8 also works amazingly well in very nearfield, likely aided by the concentric mf/hf, as you pointed out. (Not used 8030 or kh120, but I have used other models in those lines.)
I would describe the IN8 as slightly "lower resolution" than the other two, and if you look at the distortion measurements, it is worse. I think this is the closest I can get to commenting on midrange clarity. It's good, but not as good. That said, in nearfield application the concentric design is likely a win, especially if there's desk (or other vertical) bounce to consider.
I've been unlucky with *all* my used speaker purchases. I've yet to buy a used studio monitor which isn't defective in some way, or damaged in transit. I think if you're buying professional products, there's a reasonable chance they've been used as a professional tool, and thus may have been used hard for long hours, maybe with high SPL accidents sometimes occurring due to the nature of the setups and the work. So, if I were in your shoes, I'd get a new IN8 over a used Genelec/Neumann. Not for sonic reasons, but because it always becomes a headache if I try to save money by buying used monitors.
To note though, the build quality and QC of the IN8 is inferior to those two, but in my experience (I've bought 8 of them) if they are bad, they seem likely to be dead on arrival and can easily be sent back for replacement. I've not had any failures of IN8s apart from those present on arrival.
(WS12 is another story; I've owned 4, and 2 have now died within a couple of years, a 3rd is suspect and sometimes whistles, needing a "reboot" to clear it...)