I have 2 M. drouhardii and 1 M. hildebrandtii in my FL backyard. I planted them several years ago, they are huge now. I planted the two drouhardii together in the same hole due to space limitations, that was a mistake, they spiraled around each other until it looks like one is finally dominating. The hildebrandtii is larger, at least 15' taller and about twice the diameter at the base. Neither species has flowered for me. I live less that a mile from the ECFL coast, maybe they don't like the salt. They did stand up well to the hurricane-force gusts from Matthew and Irma, not even loosing any branches.
The first branches are pretty high up but reachable with a 30 foot ladder. My nursery-person skills are weak, I've experimented a little with grafting sea grape and carob without success so far. Frankly I would be leery of the weak root system from air-layering or cuttings for these massive trees. Maybe better to get your small seed importer license from the USDA and buy the seeds from India, if they cannot be sourced domestically. However maybe not so bad if if you prune the tree to spread as a large centerpiece, or if you are a bonsai enthusiast... I did the opposite since they are only 15' from power lines, now my thoughts tend more to how I'm going to get these massive bottle trees down. My original intent was to explore the Moringa genus and the possibility of getting seeds for root-stock or maybe even hybrids. Similarly my M stenopetala have never flowered, they are coppiced now. I did dig out one of those when it was about 10' and gift it to someone on the mainland, hers flowered years ago. It's been a disappointment, another another dead-end in my prolonged suburban agroforestry experiments.
My interest now is more towards improved varieties of M. oleifera. I'm trying to source the MOMAX3 variety. I'm also very interested in sourcing some Dipteryx alata seeds or seedlings. If you want to try a branch cutting from M. drouhardii maybe we can work something out. I'll be checking my messages here if you're interested.