One single pick sounds nicest to me.. but this is still a very cool experiment.
The "rubbing" sound described by the author is distinctive, more exactness across many strings isn't always more better.
Otherwise you might as well be playing a piano (in my humble, plebian rocker opinion).
I could see the double pick being genuinely useful, since it's easy enough to tip the second pick out of the way when you're only picking one string.
Reminds me of Boyd Rice's rotoguitar (a fan attached to a guitar) and the extratone genre (extreme techno kick drums that run so fast they turn into pitched tones).
This guy has done a bunch of cool/dumb instrument/tuning/etc mods, mostly with pianos and guitars. I particularly enjoyed his videos of making an electrified piano[1] and making guitar strings from spider silk[2]