Hopping on to this thread as I was going to start this myself - planning a pickup buying spree after Christmas.
I also have a PRS SVN, but mine's got an ebony board and is quite bright acoustically. I'm in the same ballpark of wanting to lose the low end muddiness and have a nice mix of harmonic clarity but enough aggression for metal.
From what I can tell, I'm 90% I want an Emerald in the neck and then I'm torn on whether to look at the Black Dog, Holydiver, Alnico Nailbomb or Cold Sweat in the bridge.
I should think you'd be looking at similar pickups - the Nailbomb has a bit of a growl to it and isn't the clearest under gain in my (admittedly limited - it's in a mate's guitar) experience, and I've gotten mixed messages on this forum regarding the tightness. Search back to the early days of the forum and the Nailbomb was the default 7-string bridge pickup, but as the forum's dwindled I've seen more recent posters question its tightness below drop C.
Black Dog is always highly recommended for baritones and drop tuning due to controlled low end and strong mids, but I'm not sure if it's hot-PAF remit carries too much PAFfiness?
The Holydiver is praised for leads and a nice thick low end, so is currently my leading contender but I'm going to try the 6-string version first.
The Cold Sweat was Ben's recommendation when I phoned about my previous PRS 7 string, but I never got to try it. Ceramic tightness without being too aggressive to be versatile.