I've recently made a change of plans for my GenCon, and I was looking at two events to play in. However, no tickets are available, so I've got to settle for generic tickets and hoping A) there's a no-show or B) the GM is comfortable with one more player than planned.
So I'm wondering: in your experience, how often do no-shows occur? One of the events I'm looking at is a Dark Heresy game with five slots; the other is a Pathfinder Society game with 30 slots.