August v. November for Rangiroa & Fakarava

[batts]

We're considering a trip to FP and are trying to decide whether to book for late-July/early-August or late-October/early-November.

My understanding is that hammerheads are most numerous in January/February, although some websites indicate that hammerhead season begins in November. I've also read that manta season is from September through mid-October, though it's possible to see mantas year round. Has anyone visited during these months? Any thoughts on whether diving would be better in early-August v. early-November?

Thanks for any information!!