What are some defining characteristics of the pickups?
Very solid, even tone. Excellent at pushing an amp into overdrive or distortion. Very tight, with a solid midrange, and very even response across the frequency spectrum.
Will deliver a very heavy hard rock, old school metal, or power metal type of tone with no issues. I would classify it as a great pickup for the
Defenders Of The Faith type of tone, if you are looking for that kind of sound, then the Cold Sweat will do it, no [cold] sweat. (Forgive the pun PDT_008)
Does the middle position with the humbuckers clean up well?
Yes, it cleans up rather well when used like that. On its own, I haven't found the CS to like playing dead clean. I have a Riff Raff, VHII, Stormy Monday, and Irish Tour to play the sqeaky clean stuff. :)