I think it's safe to say, that Joscho's picking sounds a lot different than most of the other gypsy players, like the Jimmy/Stochelo Rosenbergs, Morenos, Paulus Schafers on and on...
But I notice that most of the other big names listed above, and other old school legends in GJ, from closeups videos of their picking hand, tilt their pick down, but have the pick parallel to the strings. Josho on the other hand, tilts his pick down, but has the pick at an angle, more like a traditional rock pick grip/attack: https://www.youtube.com/watch?v=7G9RLMjzLqo
I used to hold my pick parallel to the strings, but when I angle it slightly, it does sound like Joscho's picking. It's a bit softer and smoother though, which is what I think Joscho sounds like anyways.
Anyone else noticed this?
Troy has a number of great videos about pick angle and how it's used to move between strings, especially when there are odd numbers of notes per string. His videos with Oli are worth a look too.
Joscho uses a Wegen Big City pick, which is relatively narrow, so he can angle the pick relative to the strings a little more (assuming he does). Also, he holds the pick pretty loosely -- it sort of flops backward on the upstrokes. That would surely affect the tone, too.