The deconstruction of identity is typically the concern of academics and activists, not so much magicians. But Derek DelGaudio’s “In & Of Itself,” the intimate, oft-extended off-Broadway show next to Union Square uses literal illusions to explore identity as perhaps the greatest illusion. It’s a clever conceit, and it kinda works. Through a series of vignettes, anchored by the tale of a suicidal sailor known as the Roulettista (as in, Russian Roulette), and interspersed with tricks that involve cards, personalized letters and some ingenious audience participation, DelGaudio manages a fine balance between trust and skepticism, emotion and entertainment. He’s an unassumingly compelling guide, albeit one that leans a bit heavily on the pregnant pause. The success of the show is the way it quietly subverts its generally flashy genre, employing its wizardry in the service of subtle stories with an eye to epiphany. Its aim is not (only) the external gasp of wonderment, but the internal revelation as well.