If you understand Allegiant's business model, the risk is very minimal. Virtually the only way your flight would not depart your home airport is if the airport is closed (meaning no one is flying out regardless of airline).
It is not a multiple stop/route airline. The plane is going to leave Orlando with a plane full of people that need to get to your town. They don't have maintenance and storage facilities in the spoke airports. The plane will land, empty, load, and fly back to Orlando.
We were very concerned about this when we had a freak 12-inch snow storm on the first Saturday of spring break last year. Our flight was scheduled for Sunday afternoon. We watched the delays, called Allegiant. We were concerned because if that flight didn't happen, the next scheduled flight was on Thursday. That would not be an option. We were assured that unless the airport was closed, we would fly. If it was closed, they would have plane full of people that needed to get home, so as soon as it opened they would fly in and we would be Florida bound.
Since service started here 20 months ago, we have used them to fly to Orlando 4 times. Our only delay was on the way home for our last trip. We were delayed in Orlando for an hour and a half waiting for a part to be replaced on the plane. They said it normally wouldn't be an issue, but no one was working the warehouse on Sunday afternoon.
Their prices and direct flights are hard to beat. The nickel and dime can get old, but even with reserved seats and luggage they come in at less than half the price of our other options.