I can't help you on Slipknot playing as I have no idea what it is. But I'll reiterate what Superhuman said pretty much. Unless you're a wizard at doing setups, I wouldn't even think of drop tuning a double-lock trem setup. Just changing the string gauge from 10's to 12's on my standard Strat is giving me no end of trouble on keeping the intonation right. And that has a comparatively simple trem setup.