If you really don't care where you end up sitting, I say go for the gamble. But, if you care, I just want to pass a thought: I fly often and have never seen so many seats disappear the day before a flight. I don't know where these people come from or where or how they have booked, but I have never had an empty seat next to me, or in the plane even, in I can't remember how many years when flying Delta.