Wow, the O. cocama are huge!
Just found your journal. I'm a newbie fishkeeper (~2 months in) but I love research! And my eventual goal is to breed Otos (have 5 O. macrospilus in a species-only planted tank that's matured for around a year before getting fish).
I don't know how many of these other Oto breeders you've found before, but:
james0816 on plantedtank forums
Fins And Whiskers on Youtube
Dendrochirus Zebra on Youtube
are some of the other guys I've found. (I can throw some links up if you want.)
Some interesting things I've noticed is that bioAquatix and Aquaticarts, the only two places I've found commercially selling *tank-bred otos, sell O. macrospilus only. But all the hobbyist breeders are breeding O. vittatus. (Dean's the exception with black Otos, but, well, he's Dean.)
I'm also trying to cross-reference your setup, water parameters, feeding etc. with the other few breeders. Fins and Whiskers keeps her water way cooler at 71-75F, for example, so it seems like a wide range of temperatures can work.
In the Accidental Oto tank, you don't feed any live foods (just cucumbers, Hikari algae wafers, zucchini, and Repashy Super Green, I think?) and your F1 Otos still spawned. And yet both Dean and Fins and Whiskers think that live food is key to spawning Otos. Maybe any protein source can work.
Sorry for the rant. But anyways, I'll be keeping an eye on this journal!