Can't comment on brands/thickness, but I can comment on his technique. It seems to me that Adrian uses his arm quite frequently for the majority of his picking, either for rhythm or for lead. I don't have many good close-up videos of him soloing, so I can't totally comment on his lead technique. Dave imo has a very different and study-worthy picking style, mainly because he isn't a picking purist. He definitely uses his wrist more, and he almost looks like a forerunner to some of the shred guitarists of the late-80's and modern shredders when examined closely. He prefers to use hammer-ons and pull-offs, legato stuff in general. Slides, bends, you name it. Dave likes it. Adrian does use legato, and to good effect, but he's a picker in my mind at heart. Not Paul Gilbert in deciding to pick every damn note, but still more of a picker than Dave. Janick, I can't comment on Janick.
