To add some comments in agreement of whats been said:
The Painkiller has alot of pick attack, probably the most in the BKP range. To be honest, I find it a bit too much.
The Aftermath doesn't have as pronounced an attack. The tone of the aftermath is very dry, with a full modern sounding mid range. I also believe it was designed with djent in mind, but I personally use it for a modern take on 80s metal. I don't think it would be a bad choice for technical death metal.
All versions of the warpig have smooth highs and big low end. The ceramic version makes the low end tight and adds some sizzle to the top end, but the pay off is lack of versatility. The original alnico version of the warpig sounds very nice clean and is usable for a variety of styles. I think if you're a tech death kind of guy, you wouldn't really care about cleans though.