memnoch, i find it's easier to do upstroke pinch harmonics with the pick slightly perpendicular to the string, that's when you do the "tremolo pinch picking". and it doesn't sound weird, the riff doesn't have to be as fast as a tremelo picking, but it could be easier to do stuff like the chorus of "Living Through Me (hell's wrath)" by Pantera. just as fast as that riff or faster, is where you could use alternate pinch picking.

__________________