Not only is firepay worthless, but the books place a hold on payouts for up to seven business days when using firepay.
For only a 2% charge, you can fund your Pre Paid ATM account and transfer it to a book. And you can get your money back the same day before the bank even closes if it's an early game and the book pays fast.
The only thing is be careful about getting a speeding ticket trying to make it there before they close for the day.