I love the "dark sounding" pickups - since I love stoner rock, doom and sludge. :)
I have a Gibson LP Studio with a Crawler set, a light-weight Ibanez Artist AR2000 with rosewood fingerboard and a Cold Sweat set, a mid-weight Ibanez Artist AR2618 with ebony fingerboard and an A-Pig set and a heavy-weight Ibanez Artist AR350T with Trem, ebony fingerboard and an A-Bomb set.
I was especially skeptical regarding the A-Pig set. The guitar had some Ibanez Super80s (ceramic pickups) with less than perfect wax-potting in it when I bought it. They excelled at a rumbly, growly sound for riffing, but the solo tone was practically unusable. Apart from being microphonic, the magnets were very strong and interfered with the oscillation of the strings.
Afterwards I went with an Emerald set in the guitar - but only for a short while. I'm used to hotter pickups like the Crawler and the A-Bombs and the Emeralds didn't have enough punch for me. In addition, the guitar sounded a bit sterile. I believe it would have been perfect for soaring on top of a mix, but it lacked the vocal quality and growl for laying down a stoner riff.
I had expected the A-Pigs to be a bit muffled and "cold" (as the metal sound sample on the BKP site is somewhat not my taste) but I am pleasantly surprised that they actually sound very vocal and expressive. My at-home-equipment is far from high-gain (Vox Lil' Night Train :) ), but even in its dark gainy mode with the gain set to 2 o'clock the sound is not overly compressed and even cleans up when I roll off the volume. Although, of course, it doesn't get ultra-clean (not in the dark, gainy mode) - but I like just that. :)