I would one box. Clearly spending $1000 for an expected $8000 return is generally speaking a Good Thing (tm). Over the course of my life if I always take the higher expectation value choice when offered these choices, then by the central limit theorem I will be almost certainly better off than if I generally take the lower return Sure Thing. So except for extremely odd corner cases where the sure thing is a life saver, the rational policy is to not be seduced by lower return sure things. And $1000 is not a life saver for me and actually at no point in my life has it ever been a life saver.

As a rationalist, I am afraid that if I make irrational choices I will be punished by having something bad happen to me. (It's a joke)