You can always wait until day of departure to cancel the ticket to see if the flight is delayed significantly or canceled. If it is,you're entitled to a full refund. If it isn't, then you're going to have to pay the $300 penalty to get a voucher for a future flight. Depending on when the trip is, there's also the possibility of a schedule change between now and then. One that is greater than 90 minutes would allow the option for a full refund.