As far as I know Urban Legends was the first haunt in the nation to try the idea. I suggested doing it in 2000 when I ran that haunt after having a bad year in 1999. It worked great the first 2 years. We saw a ton of customers. Then the novelty wore off. I am no longer involved with them but I don't think they offered the money back thing the last 2 or 3 years.
I think Fear Factory offers the same promotion now or a variation on it. Several haunts offered similar gimmicks after they saw the success we had with it. One haunt themed around Willy Wonka and offered a "Find the golden ticket" get your money back. Another offered a find the wizard and get a chance to win $1000.00. And a few others did the find the secret room and get your money back.
It seems once you come up with a winning formula, the competition always tries to steal the idea from you the next year. I have experienced it several times over my haunting career. It just goes with the business I guess.
The only thing I can say about the idea is that it is just a gimmick. In a new area if promoted well it will probably do well for a couple years than it will fade off.
Good luck to anyone who tries it,