Performance-art derivatives of Cirque du Soleil have become a staple of New York's downtown theater scene, but the Montreal-based troupe 7 Fingers has created something special. It's not just their amazing leaps, tumbles, balancing acts and stunts with bars, seesaws and skateboards. It's the streetwise intimacy of their presentation (the youthful acrobats, dressed in ordinary street clothes, even give us snippets of autobiography) and the way it pulls us in with the sense of danger: an acrobat plunging to the ground head first, only to be caught by others a foot from the floor; a series of leaps through a steadily growing line of rings, the occasional miss raising the tension even higher. At Cirque you sit in awe. Here you're on the edge of your seat.