Sure, let’s get the ball rolling - the first two google hits I’m getting are two pretty high quality EMG TV videos, and even if the angle isn’t ideal, the footage resolution is excellent at least.
Gotta guess a little here, but my feeling is downward slant, heavy use of economy picking:
- Pick angle isn’t a perfect predictor, but it’s certainly constistant with a downward slant
- He sweeps a fair amount, and for the most part he tends to do more sweeps from the bass to the treble strings followed by scale runs back down than up-down sweeps. The one exception that jumped out at me is in Tears of Sahara’s second solo here, but I’m not convinced those descending notes aren’t just hammered. Look at 3:45 onwards or so on Poison Cookies, where he plays a section of sweeps with descending parts, where it almost looks like the first two repeats are picked, until it’s clear that the 3rd is NOT.
- While I don’t have a good look at what the pick itself is doing at speed, particularly in the second video, “Poison Cookies,” you get some great shots of his forearm while he’s locked into a fast run… (really good stuff starting around 3:2). And I’m seeing no motion that would indicate a two-way position shift for an escaped downstroke. To be fair, as a guitarist with an UWPS default position who rotates for escaped upstrokes, I just may not know what to look for here. He DOES seem to be working the degree of edge picking with his thumb a bit, though…?
Only other piece I can add is I’ve read Macalpine’s rig was quite popular with other Shrapnel guys back in the 80s, because it was so compressed that it made faster lines feel effortless - another reason I’d be more inclined to suspect he favors a directional slant and relies heavily on legato techniques (and, watching this, his seems pretty good, I think I’d always assumed he picked more than he does) to get out of problem situations rather than using a two-way slant.
But, this is speculating based on an incomplete picture, so I’d welcome some other thoughts. 