I've actually "bred" beckfordi by giving them a heavily planted single species tank, and feeding them small food. Babies appeared and became adults in time. I had medium hard (ish) water back then. If I could get some now with my current soft water, I'm sure I could have lots of them.
They show something no one wanting to breed should forget. These are not breeds of fish, but are species. What you do with a Nannostomus from one region (let's say beckfordi) and one from another region (trifasciatus, for example) is very different. I had fry show up with beckfordi, but if I try with trifasciatus, I'm playing in a higher league. One size doesn't fit all. That's half the fun. If it were easy, they'd be guppies.