You sounds like you are looking for the Genelec 8260:
-The most accurate frequency response.
-Controlled Directivity similar to the 8351.
-Not listening as loud as some I think SPL is fine.
-If you don't want separate subs this goes to 18hz in room.
-The 8361 approaches it for extension, not the 8351.
I'm not sure if they resolved issues people brought up before with slot woofer issues compared to "normal" woofers on the pre-ones 800 series, see link below.
https://www.community.genelec.com/forum/-/message_boards/message/1004384#/
That combined with the slightly less accurate response for the sake of SPL and buried woofers and how much less the minimum diffraction coaxial on the 8260 drops when off axis compared to the ribbed ones now, leads me to believe the 8260 is the peak of engineering, and the acoustically "tri-axial" Ones series is still being perfected.
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Note: the 8C is perhaps the only other speaker I'd be curious to compare mine to, and Napilopez makes very good points about it not having as many issues as almost any other speaker when it comes to in room response. My only beef with it is the vertical dispersion because I sit on the floor, a couch, or stand periodically watching movies 6-7 feet away.