What should I wear for my 3200?

I think that even if you were trying to time trial (i.e. solo race with even splits), the Dragonfly would be better. I find kicking in the Vaporfly almost impossible - the final 200 would be tough to go around the turn, and you can't react to pace changes as well.

I'm pretty sure dragonflys are almost always faster, since in a race against others it lets you maneuver and go around better and also speeds your kick at the end. But, they also tend to trash your legs a lot, so if you are planning to race for sub 9 alone at an even pace without having to pass or stick to a pack, you could probably take either.

If it's gonna be a race with many sub 9 runners going with you and you want to be pulled through I would take the light spikes for maneuverability and kick. Also once you race in spikes vs vaporflies you kinda feel how the vaporflies are chunky when you're fatigued while spikes can keep you driving.

I should be fairly solo if I am near that 9:00 barrier. The next seeded runner is 9:31. I never really have a kick, my issue with the races has just been getting fatigued by 1000 to go and splitting some a 3:00 k after 2 2:49s (this has happened twice).

I also heel strike and personally like vaporflys more, but I am not quite as fast and don't know if they start to work less at a more aggressive pace