I see that my gamestyle is different from the usual, but at least in my current campaing, a friend of mine it's playing a Shugenja // Shadowcaster (flavour: "scorpion clan secrets" shugenja" and I found the way shadowcaster casts spells, and the way S applies metashadow quite useful.
Consider that it's gestalt*, but the campaing (paradox, maybe) it's not so power-level. Anyway, I would give him a chance even in standard campaing.
Just a note: to make him more interesting, I stated that mysteries are Shadow Wave, so work in some kind of dead magic zone.
* I mean, with another caster class aside, a Shadowcaster is more durable