for the low tuned stuff you've got options.
It depends on what kind of sound you're looking for.
The Warpig is probably your best bet. You can go ceramic or Alnico.
I have the Nailbomb/Cold Sweat combo in my Carvin 7 string and I love it
but the Nailbomb has a good amount of mids to it, so it's not all that "modern" sounding.
I wanted some versatility from my 7 and that's what Tim suggested, and it was a good suggestion. Think "Crushing Day" by Joe Satch and that's what my Carvin sounds like. the Nialbomb handles high gain very well so I can get into "Nevermore" territory pretty easily
but I do have to dial out the mids a touch to get the right sound.
Arch Enemy uses 5150's on alot of their stuff so the Nailbomb can handle that type
of tone no problemo, just crank up the gain and you're good to go.
the Cold Seat is just a great neck pickup for lead playing, probably my favorite so far (I usually go for a Duncan 59 or a duncan jazz for a neck pickup) I like the Cold Sweat better than both of those.