The cleans are much better than one typically expects even from BK ceramics (which are typically better than 'normal' in my experience)
The top end leans toward smooth and organic rather than sharp and piercing. Theres rather a lot of it though; its a bright and middy pickup, unless in a dark/bassy guitar.
Which reminds me, as an aside, its the MOST variable BK with respect guitar *that I've used* (I've only used crawler and up in output, and only used the crawler in one guitar so it doesnt count for this).
I currently have it in 2 guitars (the legras), but have tried it in 4:
Both legras, acoustically, have quite a bit (but not an overbearing amount) of low end thats very tight, fat mids and lots and lots of attack in the top end (without the acutal magnitude of the top end being that large). They differ in sound, but are closer to each other than they are to pretty much anything else I've played.
Legra MDV602:
Swamp ash body, mahogany/maple/wanut/maple/mahogany neck, ebony board, schaller 456:
Huge, tight low end, lots of top end attack, thick low mids bias with the AM bridge.
Legra Aurora:
Dark Red Meranti/maple/walnut/maple/DRM through, DRM and maple laminate wings, schaller Hannes.
With the AM: Equally huge, and(/but) tight low end, slightly more top end attack, more mid bias than the 602
Jackson SLSMG
Mahgonay through, mahogany wings, ebony board.
Note the above two guitars are moderately similar acoustically, but here we've lost the maple and the swamp ash/swamp-ash-like top end of the DRM, and the guitar is acoustically very bassy with enough clarity in the top end to balance the weight of the low end.
With the AM; tight, thick grind with LOTS of low mids and enough top end to cut through easily, but nothing like the attack of the top from the legras. This guitar currently has a c-bomb in it that sounds thin by comparison, without having any greater clarity than the aftermath in it had. I'd really like to put an AM back in this, and will get round to it at some point; it was a great sound (but it worked better in the legras than the C-Bomb did).
Jackson DX1:
Maple neck, rosewood board, basswood body, Gotoh FR.
Acoustically much less low end and much more mid emphasis than the above three gutiars and theres the trem, of course...unsurprisingly...
With the AM; enough low end comes through to ballance out the rest of the spectrum, but its pretty light on the low end front, MASSIVE midgrange grind, lots of highs but much twangier rather than attacking (trem, see).
i.e. in all cases it let the gutiar sound like the guitar sounds like acoustically, filtered through its ultra-tight, aggressive, percussive character.