Where is everybody getting this impression that there is any significant chance you'd get bumped from F? While I won't say it has never, ever occurred, to spend this much time speculating about a situation that essentially doesn't occur is misdirected in my opinion. If you buy F, your F seat will be there, 99.9999% of the time. I've never seen it not be.

What should concern you is that Delta's F service, and seat comfort, to HNL is substandard most of the time. Through November Delta is flying an internationally-equipped plane ATL-HNL that does provide a high degree of comfort. Other than that, however, the 767-400 normally used by Delta to HNL is the most uncomfortable long haul F cabin in the sky.