this is my favorite topic, as I cannot decide from clips, advice given, and what pro guitarists use.
Alot of reviews say DD is good for metal. DD has less output than the EMG 81; many use the active in conjunction with mesa triple rectifier, and like it (metallica?). I think either pup would sound good with 3xrectifier (my favorite amp), and the custom is similar to the Tom Anderson H3 ...which they use for testing out mesa amps to ensure tonality.
Reviews at harmonycentral.com say triple rec and DD and les paul is a good combo...good for killswitch engage, fear factory, slipknot, as well as sabbath...
a dude with a prs guitar, 3xrectifier and a Custom emailed me back on a question, saying he will replace his Custom for a Bill Lawrence 500 xl
...so my vote is for DD... I am far away from trying it out the combo though... any other suggestions from more experienced SD users?