Jen-I've been doing searchcactus since last Spring. They have always paid, the checks have always come when they said they would and the checks have never bounced.
You could let the money accumulate in your account, but why would you want to? There is always the chance that the program could close and you could get burned. If you think you lack the will power to sock the money away, cash the check and use the money to buy disney dollars. Then you couldn't be tempted to spend the money for something frivolous-like the rent or for groceries LOL.