One theory about that is,that the rate of combustion in relation to the piston position during the expansion stroke contributes to combustion temperatures.
The higher octanes produce peak combustion temperatures/pressures slightly later during the expansion stroke than the lower octanes, leading credibility to the the notion that octane fuels resist detonation, are harder to ignite, and once ignited have a slightly longer burn duration.
MOJO is you're going to be using the nitrous and the rich mixture it requires on all your runs you're probably best with what the dyno runs tell you.
If you're going to use gas only for some runs, and haven't done alot of recent dyno time w/o the nitrous to document horsepower readings vs timing, you might consider the higher octane gas just in case there's some detonation.
On the street it might not be worth the expense but since you're looking for max hp at the strip, it's one of those cover-all-your-bases things.