Thrash comes naturally to me, too, but DNR takes so much stamina and all it takes is one slip of the pick to throw off a whole measure. The riffs aren't too complicated, but at the speed they're at they're fully capable of rupturing internal organs if used improperly. My early playing was jazz and fusion, with some classic rock thrown in too, and I started heavily working on my technique after hearing Dream Theater; before too long I could work up any Dream Theater song to album speed with a metronome in a day or two, and I thought that there was basically nothing I couldn't tackle... then I tried to take in The Gathering. Oops.
Jeff