When DD lived in Charleston I flew Allegiant quite a few times, they are the only airline at the local regional airport. The first trip went without any issues, the next trip my flight home was cancelled after we drove two hours and arrived in Myrtle Beach, Allegiant did end up putting me up at a oceanfront hotel overnight but I had to take an extra day off work. The next trip my flight was cancelled after all the passengers were loaded onto the plane. We sat on the plane for an hour, then they de-planed us and we waited more than an hour more in the airport before they finally moved the flight to the next day. DD had already left work in Charleston to drive to Myrtle Beach and pick me up, she got halfway there and had to turn around. The last Allegiant flight I was on we were taxiing on the runway when the take-off was aborted, we returned to the gate and waited an hour for them to "check" one of the lights that had gone on during take-off. That was a nerve racking flight home.
Out of the four times I used Allegiant I had issues three of them. Each time I was given $100 voucher, when made the round trip flights under $100 out of pocket. However, the last flight I never did uses the voucher - I just couldn't talk myself into Allegiant being worth the risk.
I do know that this past winter flights from Sanford to the local airport where cancel and not rescheduled. Not worth the risk if you have a time frame that you need to adher too.