I'm not sure about the danios either. I know they can be nippy, but they usually swim in the upper part of the tank, while neons prefer mid to low area so maybe it would be okay. They/re very timid and like lots of cover in the form of plants and driftwood.

I can't see the gourami bothering them, especially a pearl, unless the pearl is huge and the neons are tiny and bite-sized! My dwarf gourami basically ignores them unless they get in his way and he just harmlessly lunges at them.

I've kept neons forever and my pH is around 7.6. They usually live for a few years. A pH of 8 is very high for blackwater fish but since so many are now commercially raised, they may adapt to it.